recordset syntax help needed

I am trying to update some reports after adding a quantity component to a donation site. I basically need to find the quotient of 2 fields (detialPrice * detailQuantity) and then SUM those amounts for like entries. Here is what I tried, and I'm getting an error that the column "pplTotal" is unrecognized.

SELECT (orderdetails.DetailPrice * orderdetails.DetailQuantity) AS pplTotal, DetailID, DetailSchool, DetailStudentF, DetailStudentL, sum(pplTotal) AS FRtotal

That column doesn't exist yet, you would have to use: SUM(orderdetails.DetailPrice * orderdetails.DetailQuantity)

it isn't working quite right. The recordset above is supposed to group entries by the students names, then return a total of all pledges made to them.

For example, if student John Smith has 2 entries in the database, one with price 50 quantity 1, and the other with price 5 quantity 10 - the result should be John Smith 100.

I assume this may be too much to do in one step, which is why I had originally tried to find the product of price and quantity, then sum the results of that operation.

SELECT (orderdetails.DetailPrice * orderdetails.DetailQuantity) AS pplTotal, DetailID, DetailSchool, DetailStudentF, DetailStudentL, sum(orderdetails.DetailPrice * orderdetails.DetailQuantity) AS FRtotal GROUP BY DetailStudentF, DetailStudentL