Check the following settings:
Menu->Settings->STB Info:
- Software version - mine is 2.64 N-1.38
- Smart Card No - see if it has some value shown (no need to show us)
- STB No - see if it has some value shown (no need to show us)
- Verifier Key - see if it has some value shown (no need to show us)
If the software version is older, update through Menu->Settings->STB Info->Settings (Red Button on remote). Then press Back, you will gate a new menu. From there choose update. Also, you may try restoring to factory settings.
Also, check Menu->Settings->Conax->Subscription Status. If it has some values along with dates shown, most probably, your card is activated. When we got the subscription, it took 2 days to get it fully activated. That was 2 years ago.
My STB is Zenega CD-1005S. Things may be slightly different if you have a different model. Did you install it by yourself?