Q: My wife has iPhone 4 in Singapore we are not able to FaceTime, any answers?

It all should work. Verified at same time and iMessage are both on. And make sure your both signed in. You cannot be signed in with the same account so make sure your wife is signed in with a different account.

This article ...

http://support.apple.com/kb/HT4319

Contains this sentence:

Note: FaceTime may not be available on devices purchased or used in certain countries, including Saudi Arabia and the United Arab Emirates.

I don't know how to tell if Singapore has FaceTime yet.

Here's further info about how to contact Singapore support:

http://support.apple.com/kb/HE57#S

Going through the stuff I sent, it looks like it should work.  Does she have the international dialing codes set up correctly (if she's using a phone number to contact you, or vice-versa)?