Error while executing User defined function

Question

I am getting the follower error when i try to exceute the following function.
[Error] Script lines: 0-0 --------------------------ExecuteCallableQuery: Execute: ORA-06550: line 2, column 8:
PLS-00201: identifier 'DWADTEST.CHECKABI' must be declared
ORA-06550: line 2, column 2:
PL/SQL: Statement ignored
CREATE OR REPLACE FUNCTION "DWADTEST"."CheckABI" ( columnname IN VARCHAR2, columnvalue IN VARCHAR2, ABINumber IN VARCHAR2)
RETURN VARCHAR2
IS
return_value VARCHAR2 (25) := NULL;
tablevalue VARCHAR2 (25) := NULL;
BEGIN
SELECT columnname INTO tablevalue FROM D_BUSI_DEMOG WHERE ABINUM = ABINumber;
IF
columnvalue = NULL
THEN
return_value := tablevalue;
ELSE
return_value := columnvalue;
END IF;
RETURN return_value;
END;
Can anybody help me?

Answer 1

I removed all inside code and try to run it. But still it is giving same error message.
[Error] Script lines: 0-0 --------------------------ExecuteCallableQuery: Execute: ORA-06550: line 2, column 8:
PLS-00201: identifier 'DWADTEST.CHECKABI' must be declared
ORA-06550: line 2, column 2:
PL/SQL: Statement ignored
CREATE OR REPLACE FUNCTION "DWADTEST"."CheckABI" ( columnname IN VARCHAR2) RETURN VARCHAR2
IS
BEGIN
RETURN 'return_value';
END;