#!Error Problem in percentage calculation from cube

[mindbender]

I`m having a percentage calculation where i`m dividing  one measure by another , the Datasource being a Cognos Cube.

Although i`m filtering for 0 values using a detail filter as well as the filter function, i`m getting a #!Error while summarizing this % column.

Also i`m getting the same error when i`m simply doing a 1/2 dummy calculation and summarizing the same after filtering the data.

What could be the problem