Blanks in Summary row

[cognostechie]

Haven't used QS is years so maybe I am missing something or maybe a feature of the new version that I am not familiar with :)

I created a calculated column with :

Operation Type - Percent

Operation - % Difference (Growth)

Expression - (Sales Current Year - Sales Last Year) / Sales Last Year

It works fine , calculates the percentage between two columns properly but the problem is
that in the 'Summary' line at the bottom of the report , it shows blanks. Does not
show the percentage of the values at the Summary line.

Any ideas?