problem

Dear all,

Thank you for your support. i have face a problem here. when i try to input

Error
1) postmaster -D mydb

error message will display as below
FATAL: database files are incompatible with server
DETAIL: The data directory was initialized by PostgreSQL version 7.2, which is not compatible with this version 7.4.1.
DEBUG: startup process <pid 1620) exited abnormally
DEBUG: aborting startup due to startup process failure

2) createdb mydb

error message will display as below
createdb: could not connect to database template1: could not connect to server:
Connection refused
Is the server running on host "localhost" and accepting
TCP/IP connections on port 5432?

These 2 above are the error that i currently face. please give me some suggestion on what should i do to correct these error.

Thank you.

Regards,
Elwyn