Hyperlink not a hyperlink?

Form field (Text66) defined as Hyperlink.
Access 2003 table field defined as Hyperlink.
Using VBA I build the hyperlink and poke it into the form field. The field displays like it is a hyperlink (blue and underlined) but clicking on it does nothing. If I open the table and click on the field nothing happens. On the form, if I delete and retype just 1 character the hyperlink functions correctly (on the form and from the table). Thinking that setting the form field = to a text string somehow removed the hyperlink attribute I then did a Me.Text66.IsHyperlink = True to hopefully force the hyperlink function. No joy.

Ideas?