I have a sumif function to return a report from a worksheet and would like to
make the condition refer to another cell (in the same workbook).

E.g.

This works...

A2: =SUMIF('Shipped Product'!A5:A100,"CustomerXYZ",'Shipped
Product'!E5:E100)

But this doesn't...

A1: CustomerXYZ
A2: =SUMIF('Shipped Product'!A5:A100,"=A1",'Shipped Product'!E5:E100)

How do I make the condition be that the range has to match what is in cell A1?

Thanks for your help.