I guess you need to be patient when it comes to PS. Are you a fresh grad? If you are, the chances are quite slim unless you have superb internship experience(s). Otherwise, the hiring timeline for PS takes a long time - can spread over 4 months (or more). My friend recently got offered a contract job under MOE after 5 months from submitting the application on C@G. So it really depends, and I would think that the process would be (slightly) faster if you knew someone in that organisation so they could help do a referral to HR. Don't give up!