subtotal in epm report problem : Index was outside the bounds of the array.

Dear all,

My report used to two reports, as the image below.

I want to display the results of the review will I14 and I17 column (as shown).

in the default report, I have used:Member sorting & grouping  for dimension colunm I.

but when I refresh the error report: Index was outside the bounds of the array.

How can I do to fix it?

Thanks,

Hung