>Are you using *nix platform?  If so, you might have to open up write
>permissions on those directories.  Can you look into your logs and see
>if there's any useful information?

>--tim

I am using windows xp. I checked error.log and I have "Internal Cocoon Problem" 
I pasted whole error here: 

"ERROR   (2008-07-14) 23:29.36:593   [access] (/gallery/ge/b.thumb.jpg) 
PoolThread-3/CocoonServlet: Internal Cocoon Problem
org.apache.cocoon.ProcessingException: Error creating persistent file for 
transformed version of file:/C:/Documents and 
Settings/gulfizer/Desktop/son/src/documentation/content/xdocs/images/gallery/ge/b.thumb.jpg
    at <map:read type="image"> - 
file:/C:/Documents%20and%20Settings/gulfizer/Desktop/apache-forrest-0.8/apache-forrest-0.8/build/plugins/org.apache.forrest.plugin.input.PhotoGallery/resources.xmap:49:74
    at <map:mount> - 
file:/C:/Documents%20and%20Settings/gulfizer/Desktop/son/build/tmp/resources.xmap:33:158
    at <map:mount> - 
file:/C:/Documents%20and%20Settings/gulfizer/Desktop/apache-forrest-0.8/apache-forrest-0.8/main/webapp/sitemap.xmap:590:44
    at 
org.apache.forrest.reading.PersistentImageReader.processStream(PersistentImageReader.java:341)
    at 
org.apache.cocoon.reading.ResourceReader.generate(ResourceReader.java:332)
    at 
org.apache.cocoon.components.pipeline.impl.AbstractCachingProcessingPipeline.processReader(AbstractCachingProcessingPipeline.java:766)
    at 
org.apache.cocoon.components.pipeline.AbstractProcessingPipeline.process(AbstractProcessingPipeline.java:429)
    at 
org.apache.cocoon.components.treeprocessor.sitemap.ReadNode.invoke(ReadNode.java:96)
    at 
org.apache.cocoon.components.treeprocessor.AbstractParentProcessingNode.invokeNodes(AbstractParentProcessingNode.java:55)
    at 
org.apache.cocoon.components.treeprocessor.sitemap.PreparableMatchNode.invoke(PreparableMatchNode.java:116)
    at 
org.apache.cocoon.components.treeprocessor.AbstractParentProcessingNode.invokeNodes(AbstractParentProcessingNode.java:77)
    at 
org.apache.cocoon.components.treeprocessor.sitemap.PipelineNode.invoke(PipelineNode.java:155)
    at 
org.apache.cocoon.components.treeprocessor.AbstractParentProcessingNode.invokeNodes(AbstractParentProcessingNode.java:77)
    at 
org.apache.cocoon.components.treeprocessor.sitemap.PipelinesNode.invoke(PipelinesNode.java:95)
    at 
org.apache.cocoon.components.treeprocessor.ConcreteTreeProcessor.process(ConcreteTreeProcessor.java:292)
    at 
org.apache.cocoon.components.treeprocessor.ConcreteTreeProcessor.process(ConcreteTreeProcessor.java:223)
    at 
org.apache.cocoon.components.treeprocessor.TreeProcessor.process(TreeProcessor.java:289)
    at 
org.apache.cocoon.components.treeprocessor.sitemap.MountNode.invoke(MountNode.java:114)
    at 
org.apache.cocoon.components.treeprocessor.AbstractParentProcessingNode.invokeNodes(AbstractParentProcessingNode.java:77)
    at 
org.apache.cocoon.components.treeprocessor.sitemap.SelectNode.invoke(SelectNode.java:81)
    at 
org.apache.cocoon.components.treeprocessor.AbstractParentProcessingNode.invokeNodes(AbstractParentProcessingNode.java:77)
    at 
org.apache.cocoon.components.treeprocessor.sitemap.PipelineNode.invoke(PipelineNode.java:155)
    at 
org.apache.cocoon.components.treeprocessor.AbstractParentProcessingNode.invokeNodes(AbstractParentProcessingNode.java:77)
    at 
org.apache.cocoon.components.treeprocessor.sitemap.PipelinesNode.invoke(PipelinesNode.java:95)
    at 
org.apache.cocoon.components.treeprocessor.ConcreteTreeProcessor.process(ConcreteTreeProcessor.java:292)
    at 
org.apache.cocoon.components.treeprocessor.ConcreteTreeProcessor.process(ConcreteTreeProcessor.java:223)
    at 
org.apache.cocoon.components.treeprocessor.TreeProcessor.process(TreeProcessor.java:289)
    at 
org.apache.cocoon.components.treeprocessor.sitemap.MountNode.invoke(MountNode.java:114)
    at 
org.apache.cocoon.components.treeprocessor.AbstractParentProcessingNode.invokeNodes(AbstractParentProcessingNode.java:77)
    at 
org.apache.cocoon.components.treeprocessor.sitemap.SelectNode.invoke(SelectNode.java:81)
    at 
org.apache.cocoon.components.treeprocessor.AbstractParentProcessingNode.invokeNodes(AbstractParentProcessingNode.java:77)
    at 
org.apache.cocoon.components.treeprocessor.sitemap.PipelineNode.invoke(PipelineNode.java:155)
    at 
org.apache.cocoon.components.treeprocessor.AbstractParentProcessingNode.invokeNodes(AbstractParentProcessingNode.java:77)
    at 
org.apache.cocoon.components.treeprocessor.sitemap.PipelinesNode.invoke(PipelinesNode.java:95)
    at 
org.apache.cocoon.components.treeprocessor.ConcreteTreeProcessor.process(ConcreteTreeProcessor.java:292)
    at 
org.apache.cocoon.components.treeprocessor.ConcreteTreeProcessor.process(ConcreteTreeProcessor.java:223)
    at 
org.apache.cocoon.components.treeprocessor.TreeProcessor.process(TreeProcessor.java:289)
    at org.apache.cocoon.Cocoon.process(Cocoon.java:557)
    at org.apache.cocoon.servlet.CocoonServlet.service(CocoonServlet.java:364)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
    at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:354)
    at 
org.mortbay.jetty.servlet.WebApplicationHandler.dispatch(WebApplicationHandler.java:294)
    at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:567)
    at org.mortbay.http.HttpContext.handle(HttpContext.java:1808)
    at 
org.mortbay.jetty.servlet.WebApplicationContext.handle(WebApplicationContext.java:525)
    at org.mortbay.http.HttpContext.handle(HttpContext.java:1758)
    at org.mortbay.http.HttpServer.service(HttpServer.java:879)
    at org.mortbay.http.HttpConnection.service(HttpConnection.java:790)
    at org.mortbay.http.HttpConnection.handleNext(HttpConnection.java:952)
    at org.mortbay.http.HttpConnection.handle(HttpConnection.java:807)
    at org.mortbay.http.SocketListener.handleConnection(SocketListener.java:197)
    at org.mortbay.util.ThreadedServer.handle(ThreadedServer.java:289)
    at org.mortbay.util.ThreadPool$PoolThread.run(ThreadPool.java:501)
Caused by: java.net.URISyntaxException: Illegal character in path at index 18: 
file:/C:/Documents and 
Settings/gulfizer/Desktop/son/src/documentation/content/xdocs/images/gallery/ge/b.thumb.jpg
    at java.net.URI$Parser.fail(Unknown Source)
    at java.net.URI$Parser.checkChars(Unknown Source)
    at java.net.URI$Parser.parseHierarchical(Unknown Source)
    at java.net.URI$Parser.parse(Unknown Source)
    at java.net.URI.<init>(Unknown Source)
    at 
org.apache.forrest.reading.PersistentImageReader.processStream(PersistentImageReader.java:298)
    ... 49 more"
Well, I confused more than ever...:S