count on dataitems

[paloalto_cognos]

HI,

I have to create a report with only counts. It has counts of 4 different kinds. Each count is placed on a singleton and has its own query.But two counts are such that they use data items from two tables which are used for joining those two same tables.

something like ,
[query6][casperid] , [query10][commiteeid] - are used for individual counts.

but product.casperid = commitee.commiteeid is used to join product and commitee tables repectively.

Now I have to substract these two count values(count[casperid] - count[commiteeid]), when I place these two dataitems in one query and count and subsrtact the output is zero . Thy have different count of ID's in each I need to show on report. also all those ID 's which do not match

Please any suggestion would help... thanks in advance