Challenge On Crosstab Query

Hope any Access guru can help me with this problem.

I want to create a cross training matrix with crosstab query in Access to show the relationship between the trainers and trainees with purpose of the trainings from the following table.

XTrainID...Purpose.............Trainer............ .Trainee
1.............Web Focus......... John................Edward
2.............Search Engine.....Mary................John
3.............CEI................... Matthew...........Edward
4............SAS................... Paul..................Mary
5.............NET.................. Greg.................Sam
6............SAS................... Jennifer..............Mary
7............SAS................... Matthew.............Edward

The resulting matrix should look something like this:

............ Greg...... Jennifer....John.............Mary........Matthew.. ....Paul
Edward..............................Web Focus...................CEI, SAS
John.............................................. .......Search Engine
Mary...................SAS........................ ....................................SAS
Sam....... .NET

I tried to use crosstab Q and picked Trainee as Row Heading, Trainer as Column Heading and Purpose as Value - with the Total option as First, but it would only show the first purpose even if trainer with the same trianee has more than 1 cross training involvement. The example is for Matthew & Edward. In this case, it only show CEI but not SAS. My challenge here is how to concatenate training purposes with the same trainer and trainee.

Any suggestion would be much appreciated.

Mike