The FileCopy command expects a file name as the destination, but you're giving it a folder instead.
In this example from my system, the first command triggers that same error #75. The second works without error.
[VBA]FileCopy "C:\Access\wip\temp.bas", "C:\Access"
FileCopy "C:\Access\wip\temp.bas", "C:\Access\temp.bas"
[/VBA]