Unable to insert Gentext in Styler 5.4

[dreason]

Arbortext Styler, 5.4 - Windows 7 - Error upon inserting Gentext

In document view, insertion point is inside text.

Stylesheet Editor has Element selected, and Gentext Tab has focus.

I click Edit Button at right side, intending to add a pound sign at beginning of text, for all instances of the selected Element. Add before [ElementName] input window appears.

I click Insert Symbol icon, or use Insert Menu, to insert symbol.

Font Family dialog box appears where I select pound sign.

When I click Insert Button, I get error in Add before window: "Insertion of text not allowed in this context".

The document, and the stylesheet, were opened yesterday and working correctly before I shut down for the day.

Can anyone help?

Thanks,

Dave