Create a function that will help me ADD values selected using a Matching Function

I am looking to do the following:

I want to write a function which will check the value of Cell A2 against the table: Sheet2!A1:J1129. There may be multiple matches. (As in Sheet2!A5 may equal Sheet1!A2 and also Sheet2!A10 may be the same value.) I want to fill in an array with all of these values, and then add up the values of Sheet2!D5, Sheet2!D10 in the above example.

The sum should be the value of that function.

Please help me figure out the function to write for doing this. I believe maybe an Array Formula could be used to do this.

Thank you very much.

Sahil Doshi.

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