Problem with report creating on PBI form

Hello,

I have a small problem with report creating on PBM:Problem Investigation form in ITSM7. I had create my own report in *.rptdesign and modify it in Birt. This is a join report, it contains PBM:Problem Investigation and PBM:Investigation WorkLog. Several days ago everything work fine, Work Log information were attached to the report, but now when I want to create a report, Work Log information are empty. If you will need more information please let me know
We are using ITSM7 Version 7.6.04 SP3 201207071337 Hotfix.

The report is working properly only when in the PBM:Investigation Worklog Data Set I set such qualification: 'Problem Investigation ID' LIKE "% [problem ticket number]%" for example 'Problem Investigation ID' LIKE "%48798%".I've tried to set such qualification 'Problem Investigtion ID' = $Problem Investigation ID$ but it did not work. The strange thing is that in PBM:Problem Investigation Data Set qualification is set to 1=1 and the data are downloaded correctly.
Is there a way to create a parameter in order to user can enter Problem ID by himself?

Please see the report file in the attachment.