Hi Martyn,

You can set conditional formatting on the button and use "The Expression" in
the Conditional Format dialog box to use the XPath count() function. You will
have to modify the expression yourself, though.

Try this:
- Open the Conditional Format dialog box
- Click on [Add...]
- In the Conditional Formatting dialog box: Leave the field in the first
dropdown selected
- Leave "is equal to" in the second dropdown selected
- Select "Select a field or group" from the third dropdown
- Select a field (e.g. an ID field) from the secondary datasource you are
using to fill the dropdown on your IP form and click on [OK]
- Back in the Conditional Format dialog box: Select "The expression" from
the first dropdown
- Modify the expression in textbox to perform formatting if the datasource
contains nodes as follows:
Old expression: my:field1 = xdXDocument:GetDOM("...")/....
New expression: count(xdXDocument:GetDOM("...")/....) > 0
- Apply the desired formatting for the button
- Click on [OK] to close all dialog boxes

Hope this helps.

Regards,
S.Y.M. Wong-A-Ton