Volvo: shiftlock overdrive, gear lever, mecanism

Question
today I could not drive away, because the gear shift lever was blocked. I managed to drive away by pressing the shiftlock overdrive. It is still the same now, after driving some kilometers.
Question: what makes the gear lever to be blocked. Is there something wrong with the car, that the lever is blocked? Do I handle something wrong to make this lock blocking the gear lever. Do I have to see the garage to get it repaired? Hope you can help me. Regards Paul

Answer
Hi Paul,the shiftlock is electronically controlled by the brake light svitch(after you svitch on ignition),the problem could be either the brake light svitch or the shiftlock mecanism(below the level),you are not damaging anything,but my advice is have it checked.