Hi Harsha,
As I understand problem is not clearing old values before assigning.
you will get correct value when you execute with selection because at that time it will process only once so you will get correct value.
you will get wrong value when you execute with multiple selection(like for one month) because at that time it will process multiple times hence old values also adding and so clear before every new assignment.
Please debug your code and if your not comfortable with ABAP seek help from others.
Hints:
Before populating values for L_ZCGU + L_ZCTU + L_ZCNU + L_ZCQU first clear and then assign as like below.
Clear : L_ZCGU + L_ZCTU + L_ZCNU + L_ZCQU.
and assign.
and then use
RESULT = L_ZCGU + L_ZCTU + L_ZCNU + L_ZCQU.
Thank you,
Nanda