Calculating average at BEx report

Hi all,

We are to trying to derive average of quantity at line items for a transaction as follows.

For ex. for transaction ID 110012 the avg quantity is (20+80+100+80) / 4 = 70.

70 needs to be stamped for each line item corresponding to than transaction ID.

We created a formula 'Average Qty' as only qty and exception aggregation as average. But only when items are removed, the average is showing.when If line items are added the average isn't coming up for each line item.

Is there anyway we can resolve this.

Thanks,

Akshara