Native SQL - CONNECT TO command

Hi Gurus,

I am trying to access a third party database with Native sql. Basis has set-up a DBConnect with this database. When I tried to coonect to this databse, statement(CONNECT TO) showing sy-subrc = 4. My connection testing program is given here.

REPORT zbw_sd_test.

PARAMETERS: con TYPE dbcon-con_name.

EXEC SQL.

connect to :con

ENDEXEC.

WRITE: 'Sy-subrc = ' .

WRITE: sy-subrc.

When I chose another databse connection name, it is showing sy-subrc = 0.

Is that the problem with improper DBConnect?

How can I identify the reason for 'sy-subrc = 4' in CONNECT TO statement?

Pls guide me..

Thanks..

Saj