search builder returns incorrect count

database has conributions with a source tag of "mailing". There are a total of 126 as found by a direct select using mysql command line. Using search builder the returned count is only 104 but, the list of items is complete. There are 104 individulas and 22 households in the database. It looks like the households are not being included in the count.

select count(source) from civicrm_contribution where source = "mailing"

;
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With search builder
select civicontribute
then contribution source
use the = operator
string of ""mailing"

Count is 104