K-1 will not uncheck boxes

[TMC1100]

In filling out my K-1, I had information on Line 19 and a Z code for Line 20.   The notes for 20Z say there were no qualified business income or loss for purposes of section 199(A).  So I posted a 0 for line 20.  In turbotax Federal review, it is catching it as an error.  I when back to the K-1 and tried to uncheck the box 20.  It will not allow me.  Other lines I can check and then uncheck but Line 19 (which I want to keep) and Line 20 will not be unchecked.

Suggestions?   Thank you

[VolvoGirl]

Did you delete the 0?  Put in a space.  You might try deleting that K-1 and enter it.