SAP Message GB308 - User exit & not declared in form pool &

Diagnosis User exit &V1& is either not defined or not declared in formpool &V2&. System Response Code for calling up the user exit is not generated or the selectioncheck contains a syntax error. Procedure You define your user exit when you create user exit &V1& in formpoolV2, which is entered in table t80d. You declare your user exit &V1& or the passing parameters required forit when you make an entry in the FORM routine GET_EXIT_TITLES informpools &V2&. You can find more information about user exits under the keywordUser exit formpools .

100931	Missing buffer synchr. for import post handling
167042	Validatn exit pool name may not exceed 8 characters
48121	User Exits in Validations/Substitutions