Login script for agent deployment

I have written the following login script for the self created agent deployment. However, it does not work.

I always run the agent file in every time, even it has been installed as before. Is there anyone know the reasons?

@echo off

If exist c:\Program Files\LANDesk goto done    -> this statement is invalid, it cannot skip to the end of the login scipt even it check for this folder is existed.

cls

@\\DCServer IP address\\LDlogon\Agent file name.exe

:done

exit

Best Regards