fill utility doesn't work on usr fields

Dears, when i made fill utility on fields created in USR layer , i faced the following problem

Error executing code: SysDictField object not initialized.

(C)\Classes\SysDictField\combinedTypeId

(C)\Forms\SysFillUtility\Methods\init - line 48

(C)\Classes\SysSetupFormRun\init - line 3

(C)\Classes\MenuFunction\run

(C)\Classes\FormFunctionButtonControl\Clicked - line 11 need your help for urgent.