Behavior of an empty calculated field during searching

[ConnerDA]

I was hoping for some insight into the following issue.

I am working with Filemaker 11 Advanced.

I have a table with a calculation field using the Sum(field) calculation. The result is set to number and sums values from related number fields. Depending on the related field the result may be a decimal number or nothing (i.e. no related fields so no value). The numerical value from the calculation is correct. However, I have problems when performing searches on that field. For example, I can find all the values that are >0. However, the search fails if I search for all records with no value (=), even though there are many records with no value.

I have tried changing the calculation to a conditional calculation that results in 0 if the Sum(field) calculation does not result in a value greater than 0. The expected result is displayed, but the search still fails. For example, if I search for values that are <= 1, it returns all records with 1, but not those records in which the value is 0. I have double-checked to make sure all the related fields are defined as number fields. I had thought originally that it may have been a text vs. number issue.

Any ideas?

[comment]

the search fails if I search for all records with no value (=)

I don't know about that. Does the attached work for you?

BTW, that's not the best method to find records with no children.

Find.zip