I want to add more fields to filter

i want to add more fields to filter in a list page . when i am trying to add fields that means clicking on more in filter i am getting an error (C)\Classes\SysFieldManager\BuildFieldTree - line 25

Can you tell us what error you are getting? Is that a standard list page?

You should be able to debug the mentioned class/method to know more about the issue.

FormGridControl object not initialized.

Stack trace

(C)\Classes\SysFieldManager\BuildFieldTree - line 25

(C)\Forms\SysAddFieldForm\Methods\run - line 4 this is the exact error .it is not standard listpage.

Can you show us the screen shot of the design?

It seems the grid is not initialized in for loop in \SysFieldManager\BuildFieldTree

You can compare it with a standard list page.