Hi Glenn,

I found out what went wrong at last !!!!

i went to Tools> Options > Calculations. there, i found 'Accept labels in formulas’ checkbox unchecked. i checked the checkbox and then copied the formula once more into the relevant cells and the problem got resolved.

but why 'Accept labels in formulas’ checkbox got unchecked on its own in the first place is what i don't understand.

Thanks once again Glenn for your constant support

Regards,
Geetha