What am I missing?

In a repeating table I am able to ;-
selectively fill cascading dropdown lists
selectively fill  an expression box
Based on data filtered by selection in the initial drop down list using
the current() function.

When I try to fill a text box in the same table location and with the
same rules the result (in the text box) is always null when using
current(). Without using current() a value is displayed but of course
the data is not linked correctly..

Have used several data sources (xml doc) to no avail

Anybody have a magic bullet?

Casey