To execute the current Script, press F9 or use the RUN|execute menu or its associated button on the toolbar.
The essential condition to be able to generate a diary is that there remain no error messages in the Messages Window. The RUN|execute menu or its associated button on the toolbar will remain disabled as long as there are error messages in the Messages Window.
If you have a large script (many pages and/or many ScriptLines), and you are concentrating on getting one particular grid done (or re-done), then you can choose to only generate a single scriptline or to generate only the first x pages of a full script or of a single ScriptLine.
Clicking on the OK button starts diary generation.