What exact form must the SUMIF function take in order for the summation condition to be unloaded from the adjacent cell?

Question

Google Sheets

Hi there, got over the mishaps with the SUMIF formula:
Now the formula looks like this:
=sumif('Sheet2'!B6:B1001;" VKSept ";'Sheet2'!J6:J1001)
It sums the values ​​from the second sheet and outputs them to Sheet1, when In this case, the conditions are in the range B6:B1001, the summation range is J6;J1001, and the condition itself is VKSeptember;
The formula works;
It is necessary to change the formula so that the condition is loaded from another cell on the first sheet;
View =sumif('Sheet2'!B6:B1000;"=(INDIRECT("Sheet1!"B7;true))";'Sheet2'!J6:J1000)")" - doesn't work; Indicates a syntax error;
Tell me, please, is it possible to implement this in principle, and what needs to be corrected?