inscrutable error filling in Colorado return

TT reviews my CO return and tells me I need to fix an error. 

"Check This Entry:
  Credits Wkst: Homeex must be entered."
This is followed by three radio buttons:
[x] No entry (selected)
[ ] Snr Hs Cr St Wk Ln1, yes

[ ] Snr Hs Cr St Wk Ln1, no

I assume there should be a "credits worksheet " with a line 1 that has actual words and I could figure out which one to check. But in State Forms I've got no such worksheet, and none of the forms has line 1 that maps to those abbreviations in any obvious way. Can anyone decipher this?