Drag Drop

I have mulitiplicy KVM.  Everything was working fine until I had to reformat my primary PC and reinstall all software.  Now, the mouse moves from primary to secondary PC no problem but I am unable to drag n drop from primary to secondary.  Drag n Drop is the only features that doesn't seem to work, since reformatting my primary PC.  Drag n Drop feature is enabled in primary, but it fails to work.