beforedoubleclick event does not trigger

I want to get a calendar object to pop up when a particular cell is double-clicked.
I have found many snippets showing this and the calendar /userform are fine but the beforedoubleclick does not run the code.
I have checked for locked cells security and protection but nothing is enabled to prevent cells from being written to. But that is assuming that the calendar would appear.
If I ran UserForm1.show it appears and a button on the calendar object enters that date into the target cell, all that is missing is to make the thing appear in the first place.
Any ideas why the event doesn't trigger the code

Thanks in advance

Hi Dominic thanks for the speedy response
At first I put it in a module I added in the VBE and after I put in the THISWORKBOOK neither worked
I started with a completely new workbook as far as I am aware there are no other evenet driven modules.

This is a piece of code that I tried

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Dominic thanks for that works fine the byval thing was my mistake not paying attention having tried copying and pasting and modifying so many times.
The worksheet code was something I was musing over for a while as I wasn't sure how it differentiated over one sheet from another so i assume it's the local sheet

Thanks again