Interview time of spouse at Singapore

[abra]

I am permanent Resident. I have sponsored for my husband who is living in Bangladesh and got letter from Singapore that they will call interview.
Accordingly, they will let us know the schedule. I have applied in May 2007; this is 4 th months running. How long require to wait for interview at Singapore. My friend sponsored for her husband they got visa within one and half months.
I am worried! Hope you can understand.

Thank you.