Pass File_upload field as function parameter

Pass File_upload field as function parameter

Hi,

I can't pass a File_upload field as function parameter. I need it to do the proposed workaround to preview a file:

https://help.zoho.com/portal/en/community/topic/how-to-open-a-pdf-file-of-a-view-in-preview-mode

Why is it not working?

I activate the function through a custom function button found in a report. The File_upload field is shown in the report, but I can't select it as a function parameter.

Thank you for your help!