Having trouble with variables on XLSM workbook with custom XML

I know this is a basic question but I am currently having difficulty understanding variables in the following situation.

I have a XLSM containing a custom XML. The XML code is irrelevant to this question except that the first line reads:

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I have a module containing the RibbonOnLoad code thus:

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I wish to move the bulk of these lines to a separate procedure which is called from the RibbonOnLoad. Below is what I would like to achieve (or close to it):

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However using the above code creates errors. I know the solution should be obvious but I am not getting my head round it.