Did you try to run under %COMSPEC%? You will need to do this if you want to expand environment variables on the command line.
You also need to ensure that the environment variable is available - it depends on how you set it.
You will also need to protect the command path if it contains spaces.
Your SHELL command should look like this:
Code:
Shell '"'+%COMSPEC%+'" /C "'+$cmd+'"'
If @ERROR "Got error in SHELL: ["+@ERROR+"] "+@SERROR+@CRLF EndIf
