The Microsoft Script Debugger is required to be installed on the client to debug script running on a mimic (VBScript or JScript). After installation ViewX must be restarted for the changes to take affect.
A simple way to find out if the script debugger is installed is to display a mimic with scripting enabled on it, put the mimic in run mode and display the debug tool bar. If the script debugger is installed then the left-most icon in the tool bar will be enabled, such as in the screenshot below (the icon below the yellow OPC icon).
Clicking the icon will display the script window.
The script debugger installs to "%ProgramFiles%\Microsoft Script Debugger" (usually C:\Program Files\Microsoft Script Debugger) by default. The installer can be downloaded from the Microsoft website here.
Once installed , the full script debugging environment will be available.