Since upgrading to CA Client Automation R14, I can no longer Drag and Drop files when creating software packages.
This is the expected behavior for R14 and higher versions.
Starting from R14 we have changed the Dsm Explorer to run with elevated privileges to improve other functionality.
CA Client Automation - R14 and higher versions
As a work around the Copy and Paste Function can still be used.
The option still works if your Account is a Local Administrator, so you can change the Account to be a Local Administrator
Please refer to this acticle for further information: