Crystal Reports Combination Calculations

Message

   Dear All,
Can someone help me with following issue:
I have a report which contains data about orderlines within an order.
Report has a Group Header1 on Orderlevel.

For Example: 
Order 1:
order 1 line 1 ProductGroup X
Order 1 line 2  ProductGroup Y
Order 1 line 3 ProductGroup Z
Order 2:
Order 2 line 1 ProductGroup Y
Order 2 line 2 productGroup Z
Order 3:
Order 3 line 1 ProductGroup X
Order 3 line 2 productGroup Z

I want to create a matrix which tells me how many orders are occurring in a certain combination of 2 Productgroups?
                         ProductGroup X  ProductGroup Y  ProductGroup Z
ProductGroup X              2                     1                      2   
ProductGroup Y              1                      2                      2
ProductGroup Z              2                      2                      3

So, if you look to the example data:
Productgroup X with productgroup X has 2 orders.
Productgroup X with productgroup Y has 1 order.
Productgroup X with productgroup Z has 2 orders.
I tried with a crosstab but could not get the desired result.
i have approx. 30 productgroups.
Does anyone have an idea how I can solve this?

regards 
Memoli