Duplicate check in dynamic data linking is not working properly

I am trying to build a form that will check the duplicate like participant id, nid , mobile number as my project needs these field to be unique. at first it worked properly. so I left the project as it is and was waiting to circulate the project today. But unfortunate when i checked it today before circulating at the last moment , its not working properly any more.
this is the format of forms:
Form 1.
Loan_Registration_Form_V5.xlsx (37.3 KB)
Form 2.
Training form_V5.xlsx (40.0 KB)

please note that, form 1 is linked to itself and form 2 is linked to itself and form 1.
I cannot quite find out what the problem is. Please help in this matter

@mahbuba_pksf, maybe you could check this post discussed previously; it should help you solve your issue:

Dear Kal lam ,

I have read this post at least 30 times and spent hours for 2 weeks and worked on trial and error basis while was building the forms as it was my first time building a form in Kobo Toolbox. At last i got it right. And it was working just fine. But the questions were not grouped then when i was building them. Probably the problem raised when i grouped my question and as per the convention i added the group name in the dynamic data linking. All the example given in community forum are duplicate checking and data pulling from parent to child on ungrouped questions. I am assuming that i am missing to see to a small thing. That’s why i made that post. Will please kindly check the forms and see what is the point that i am missing. I appreciate your efforts.

Thanks and regards,