Error of repeat-group

Hello Dears,

I have a form with group inside another group but the attached error come up while try to open the form in Kobo application in mobile phone. any solution please?

Welcome back to the community, @iraq_habitat! Did you validate your XLSForm through this online validator? The online validator should help you find the syntax issues if any are present.

Yes I validated with no error but the error come up in Kobo mobile application