Reports :: Can't Average Blocks Of Weighted Grades In Report

I'm having a problem getting a report textbox to display the average value that I want.

Background:I have a DB that tracks student grades. The course is organized into blocks, with several tests in each block. Students can take the same test multiple times, in cases of failure, or if they get rolled back in class. The DB tracks whether or not each test is a retest or audit.

The tests are also weighted. For example, the Geo Quiz could be worth 10% of the grade for a block, and the final exam 90%.

Goal:My report needs to display the class number, student name, block, test, and associated scores; it needs to show the total grade for each block; and it needs to display the student's average grade across all blocks. I need to be able to generate the report at any point in the course, not just after all blocks and tests have been completed.

Setup:Since I want to display the assigned grade, but calculate the weighted grade into the block grade, I set up a query (qryWeightedGrades) to calculate the weighted grade for each test (e.g. Score of 98%, weighted at 10% of block, results in a 9.8 for the weighted grade). When it comes to calculating the block grade, I just sum the weighted scores.

In the report (based on qryWeightedGrades) I have the grouping levels set up for Class#, Student name, then Block; the test name, score, weight, retake info, audit info, etc. appears together on a row.

How to do, get the average of all the block grades. I can't get the textbox in the Student Name group level footer to average the Block grades in the Block group level footer, without getting an error. I've thought of creating another query that averages the block grades for each student, but how to incorporate that into the footer of the Student Name group level.

Here's an example of what I want the report to look like:

Class#: 13010
Student Name: Smith, Peter
Block: WF101 (4 tests in block)
....Test: Quiz1, Score: 95, Weight: 10
....Test: Quiz2, Score: 90, Weight: 10
....Test: Essay, Score: 80, Weight: 40
....Test: Final Exam, Score: 85, Weight: 40
Block Grade: 85

[code].....

Student's average grade: 91.93 <--Getting this # is giving me problems

Class average grade: ##.##