Samsung sim card problems?

When I get my orange sim card out of my other phone, and try and put into my Samsung e900, which is on Vodaphone, I put the batteries back in ect but when I turn on my samsung it says invalid sim card. Whats the problem?
Update: Also when it has it's normal sim card, it says Limited service. I bought it myself from Costco, so it's not stolen..
2 answers