XUpload - have unallowed extension! Skipped

[Lolo]

Hi,

I just purchase XUpload Pro and installed it on my server (LAMP).
It works well, but I have to restrict allowed extensions to only one (mp4)

I put the ext_allowed variable to 'mp4' in the XUploadConfig file.
The control is OK in the form (as a js alert), the upload seems to be good but at the end, the file is not uploaded. When looking at logs.txt, the message is "have unallowed extension! Skipped".

Thanks for your answers