From stinem1 via forum:

Equation question with the following:
{sumifop(">", 0, B1.valueNAOK, B2.valueNAOK)}

If I select the answer for B1 that gives me a score of 1000, and the answer for B2 that gives me a score of 1000, I get:
"010001000" instead of the sum of the two scores, 2000.
It appears to be correctly selecting the answers I want, but instead of adding them as values, it is joining them into a string.

If I use {sum(B1.valueNAOK, B2.valueNAOK)}, it works just fine, but obviously isn't filtering for the scores greater than zero.