SDM password error

I am trying to "Deploy New Archive and Run" a Web Dynpro application from NWDS. I get the following error when I entered the password for SDM.

Deployment exception : Server sapdev did not accept login request as admin on port 50018. Details: ERROR: Could not establish connection to server sapdev at port 50018: sapdev

Inner exception was :

Server sapdev did not accept login request as admin on port 50018. Details: ERROR: Could not establish connection to server sapdev at port 50018: sapdev

Any pointers on what might be wrong?