BP Model Extension - Data disappearing

Hi,

I have extended BP model and done following.

1. In customising added 5 dependent nodes.

2. Implemented Classes for these nodes

3. Created a Z component and created Table assignment block based on nodes.

4. Integrated Z component to BP_HEAD

When I click at INSERT button in my table assignment block it adds a empty line , now I enter data and then click INSERT again to add another row. I can see that control does come to MODIFY method and process all steps and  I add object to CT_CHANGED. Now when controls comeback to UI data entered before is disappeared . I can see 2 empty rows.

I have look at my code through out many times but unable to find out reason.

Any pointer is appreciated.

I am working on CRM 713 SP1.

Thanks in advance

Deepak