Actually, the += and -= are perfectly legit for the animate method. They allow you to animate a property relative to its current value. http://docs.jquery.com/Effects/animate
I believe the "margin-left" is the throwing it off. Somewhere in the docs it mentions hyphenated properties should be written in camel case, with no quotes. So: $(".items").animate({marginLeft:"+="+amount+"px"},"slow"); And, as per HTML spec, your tabs' id attributes should start with a letter. That might not cause any issues, but it's better to follow the specification. http://www.w3.org/TR/html401/types.html#type-name Hopefully that's enough to get your script working. If not, try installing the Firebug plug-in for Firefox and litter your code with console.log("some text or element") statements to see what is/isn't being fired/passed around. Make sure to comment them out or remove them before publishing. :) Beyond that (not related to your problem -- just unsolicited advice), you may consider using the id on the item elements and having your tabs be anchor links with an href="#id" ... to make it work with JavaScript disabled. Brian. On 2/14/08, andrea varnier <[EMAIL PROTECTED]> wrote: > > > > $(".items").animate({"margin-left":"+="+amount+"px"},"slow"); > > I really hope you can help me, I had never encountered this problem > before. > > > try and take away those '+=', you wouldn't write a css rule like this > > margin-left: +=300px; > > :) >