Only part of data is displayed in matrix

Hi,

I have a dataset, which is a parameterized stored procedure. It takes campagin_id, number_of_winners (n) and correct_answer for parameters and retrivesn random winning users' data in the following format.

username    email    question_number    answer

The number of questions for different campaigns are different.
When I display the data in a table, all the data is displayed. But I want the data in a format where the question numbers are headers and the answers are displayed in the relevant columns. E.g.

username    email    answer_for_q1    answer_for_q2 ...    answer_for_qn

So I created a matrix as follows (column group on question number):

                                |question_number
username    email    |answer

The problem is, that only part of the data is displayed in the matrix. E.g., if I have a campaign with 8 questions and I want 10 winners, of course I should get 10 rows. I never receive it. Moreover, the number of rows displayed change.
In the table I have all the needed 80 rows (8 questions X 10 users).

Could anyone clear the confusion in my head?

Thanks.