Hi James!
Finally it wasn't the copy file command, but the files that i was trying to copy. Those were the DWGs, AutoCAD files. And in the array we had the doubles,
it wasn't no more 50 but up to 250 files(Don't ask me , i don't know why). So the only think we had to do is to check for doubles.Bla-bla-bla...
Thank you for your time.