Bug 28264: Transaction type is empty is cash register statistics wizard report

Bug 28264: Transaction type is empty is cash register statistics wizard report

To test:
1) Go into a patron file and add some manual fees and pay them
2) Go to Reports > Statistics wizards > Cash register
3) In the form, choose Transaction type: All transactions
4) Click "Submit"
5) Note that the Transaction type column is empty
6) In the form, choose Output: To a file
7) Click "Submit"
8) Open the file in a spreadsheet software (I use LibreOffice)
9) The Transaction type column IS NOT empty

Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>