problem with php

Hi I do not think you are equiped to handle this problem, but I cant work out from the php documentation, where the communication should go, so here goes. Maybe you can direct it to the appropriate recipient. I opened a website with a hosting service recently. The site was running php version 5.2.9, but for reasons not relevant to this problem, the host transferred the site to another server, also running ver 5.2.9. Running in the earlier server, the site was performing satisfactorly and among other operations, was carrying out file uploads from a local PC. When the host transferred the site to the second server the file uploads ceased to work. The php stalled on a line in the php script "is_uploaded_file($imagefile) wih the error mesage "undefined variable:imagefile". This never happened in first version. Can you offer an opinion as to what could be differences between the two php instances that would cause the error in second one and not the first when they are both the same php version? Rodney Courtis