Sum of sales where comments is null(-)

[Rav3]

I have to do the summation of sales where Comment is '-' (its string) 

=SUM({<COMMENTS={'-'}>}Sales)

=SUM({<COMMENTS={' '}>}Sales)

Both the  Expressions are not working  Please Advise.

Thanks

[Rav3]

=SUM({<COMMENTS={'-'}>}Sales)

=SUM({<COMMENTS={' '}>}Sales)

Both the  Expressions are not working  Please Advise.

Thanks

[afurtado]

Hi.

Try this

SUM({<COMMENTS -={'*'}>} Sales)

or

SUM({ $ - <COMMENTS ={'*'}>}   Sales)