Your device is on a BES I'm assuming. Are your contacts syncing fine? Any other problems besides for the wireless sync on the calendar? Personally, I would do the following if everything else works fine.
1. Call your IT Department and have them resend your service books.
2. Call your IT Department and have them reset your Enterprise Activation password. I would then Enterprise Activate the device to see if it works.
3. make sure that wireless is enabled on the BES as well.
if this is a company issued device, your IT Department should be troubleshooting this...