Cognos 10 Report Studio Cross Tab error

[vummadis]

In the Cross Tab report, I am trying to summarize the Totals. But it is NOT working & throwing error message.
Please find the error message in the attachment.
Steps Followed to Create the Cross Tab.
1. Dropped the Regions Column into the Rows
2. Dropped the Review raing field onto the Columns
3. Percentage field onto the Mesures.
Percentage fileld is the ratio between 2 other Data Items. When I try to summarize the Measure field, it is throwing the error.
Please help me as this is highly important and need to resolve ASAP.

[karthik.kadambi]

I don't think you can do a Summation on the Measure field. It has to a Data Item occurring as a Row or Column