Call Method from other method defined in same class.

Hi all,

I'm trying to call a method from other method defined in the same class using class object. But its showing error message saying class object is not defined. let me explain you with example

Inlucde xyz.

class c1 definition.

methods : a1,

b1.

endclass.

class c1 implementation.

method a1.

endmethod.

method b1.

call method obj->a1. -> Error is here Field OBJ is unknown not defined by DATA

endmethod.

endclass.

include abc.

data : obj type ref to c1.

create object obj.

call method obj->b1.

program klm.

include abc.

include xyz.

Can anybody please let me know how can i call one method from other method.