18 December 2008 at 10:56pm
Finally I debugged the SWFUpload.js and discover that the error is in the function SWFUpload.prototype.browse. When it try to movie_element.Browse(); it receives the next error Error calling method on NPObject! [Plugin exception: Error in Actionscript. Use try/catch block to find error].
My solution is to download the latest silverstripe sources and replace the content of the directory jsparty/SWFUpload with the last one.
It solves my problem. I hope this has not negative implications in other aspects of my Silverstripe 2.2.1 version.