This is such a simple code that compiles correctly, but I'm getting the error below when running it :(
TypeError: Error #1007: Instantiation attempted on a non-constructor. at mx.controls::ProgressBar/createChildren()[E:\dev\4.0.0\frameworks\pro jects\framework\src\mx\controls\ProgressBar.as:1110] at mx.core::UIComponent/initialize()[E:\dev\4.0.0\frameworks\projects\fr amework\src\mx\core\UIComponent.as:7250] ...... Here's the code that gives this error: <s:TitleWindow ...> ..... ..... <s:controlBarContent> <com:IconButton id="btnAdd" toolTip="Add file(s)" click="addFiles()" icon="{addIcon}" skinClass="com.skins.IconButtonSkin" width="20"/> <com:IconButton id="btnRemove" toolTip="Remove file(s)" click="removeFiles()" icon="{removeIcon}" skinClass="com.skins.IconButtonSkin" width="20"/> <mx:ProgressBar id="uploadProg" labelPlacement="center" width="100%"/> <com:IconButton id="btnCancel" toolTip="Cancel upload" icon="{cancelIcon}" click="onUploadCanceled()" skinClass="com.skins.IconButtonSkin" width="20"/> <com:IconButton label="Upload" toolTip="Upload file(s)" id="btnUpload" icon="{uploadIcon}" click="uploadFiles()" skinClass="com.skins.IconButtonSkin" width="20"/> <com:IconButton id="btnView" toolTip="Show/Hide file(s)" click="changeView()" icon.full="{viewIconFull}" icon.mini="{viewIconMini}" skinClass="com.skins.IconButtonSkin" width="20"/> </s:controlBarContent> </s:TitleWindow> If I remove the progressbar code from here, it runs fine. But with that one line, I get above error during runtime. With this line in, even the Design mode doesn't show-up in Flash Builder 4 :( Any idea what could be the issue here? PS: I've tried with the normal s:Button as well, before the skinned button component. So obviously those can't be the problem.