PERFORM a paragraph in other file ?

Hi everybody.

I have 2 files as below :

1. MAIN.cbl 

2. SUB.cbl

In MAIN.cbl :




   display 'HELLO EVERYBODY'.

In SUB.cbl : I want use HELLO-PAR paragraph and don't want code again it. I try to PERFORM HELLO-PAR but have error.

How do this ? Plz show me. Thanks !