'Create' Push button is not working in BDC and LSMW while uploading G/L master data

Hello Experts:

I am facing the following problem:

While uploading G/L master data with the BDC program, 'create' push button is not working  even after executing following lines.

PERFORM BDC_DYNPRO      USING 'SAPLGL_ACCOUNT_MASTER_MAINTAIN' '2001'.

PERFORM BDC_FIELD       USING 'BDC_OKCODE'

                               '=ACC_CRE'.

Create G/L account  screen is not coming in BDC. Please suggest me what to do.

Thanks !!