I found my problem and solved it, now it update automaticaly…
the problem => Download Accelerator Plus , this app put an hook inside the HTTP/DL protocol of IE to “accelerate download” but the achat updater don't understand the message from that app and say => can't download the file. (basic explain, it's more complicated)
how to solve => unsinstall the program.
@sebek :
if you have an download accelerator, remove it totaly.