Chris,
In your calculated field use iif(isblank(yourfield), null, yourfield) as the expression, and then chek the avg. This should work (zeros will count, this will skip only blank fields, if you don't want them at all replace the expression with iif(empty(yourfield)... or iif(yourfield=0...)).
HTH
Hugo
"The five senses obstruct or deform the apprehension of reality."
Jorge L. Borges?
"Premature optimization is the root of all evil in programming."
Donald Knuth, repeating C. A. R. Hoare
"To die for a religion is easier than to live it absolutely"
Jorge L. Borges
