Displaying Grand Total in SSRS 2008 R2

I have "Tablix1" which gives sum of the Tablix1TotalAmount field and I have "Tablix2" which gives sum of the Tablix2TotalAmount field. I need to get the sum of these two Total Amounts in say TextBox, Grand total. Example: Grand Tota开发者_开发问答l = Sum of (Tablix1TotalAmount + Tablix2TotalAmount)

Please advice, what expression should I specify in Grand Total.

Thanks, Ken.

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How about something like this?

=SUM(Fields!Tablix1TotalAmount.Value, "Tablix1") + SUM(Fields!Tablix2TotalAmount.Value, "Tablix2")