Element Reference from XML File not working

I am trying to pull an image in using url from xml on my BI template using the alt text.  I am using BI Publisher Word (Office 365 ProPlus)

I have set the alt text to:  url:{SignaturePath} and it will not work.

If I enter url:{'\\pd-japp01\BI_Publisher\NEFS_LOGO\Signatures\Ryan.png'} it works fine.

This is the XML path information:

<SignaturePath_ID103>\\pd-japp01\BI_Publisher\NEFS_LOGO\Signatures\Ryan.png</SignaturePath_ID103>

Any help would be much appreciated.

Tina