After complete upload reload progress bar if not complete error

Question

Hello,

A friend of mine had made this application and it is working fine until I found out that after uploading or not the progressbar stays 100% and some files are uploaded and some not... But I dont know when it has failed or not... I want to get the progressbar start over (at 0%) after a good upload and a message after a bad upload but I dont know how...

I'm not a C# specialist so maybe someone can help me out here... I think the files in the attachment are enough en if not please tell me..

Thanks in advance!