@LDRIVE is populated automatically, there is nothing special you need to do.

Is @LDRIVE available once login has completed? Perhaps you have a timing issue and the drive is not (yet) available? You may need to set the login script to run asynchronously.

We've had odd problems with the netlogon shares not always being available during login since switching from NT to an AD structure, so I tend to use "\\mydomain.com\sysvol\mydomain.com\scripts", which appears to be more reliable.