I am trying to use xcopy and it always returns with invalid drive specification
xcopy "C:\socp.tar" "\\FMDX1024\C\socp.tar"
FMDX1024 is a machine on the network.
If I put in a valid path, XCOPY completes successfully for me.
If I purposely put in an invalid path, XCOPY returns, "Invalid drive specification".
So guessing what you think you have, you do not. Either the \\FMDX1024\ or C\ is incorrect (& it need not be "C\", it could be called anything).
C:\TMP>xcopy xxx.txt \\therube\c_drive\tmp\xxx.txt
1 File(s) copied
C:\TMP>xcopy xxx.txt \\therube\c\tmp\xxx.txt
Invalid drive specification
0 File(s) copied
C$ is an Administrative share, which must be enabled by undoing Simple File Sharing.