Vor Advice

I did try the search, but I could'nt find a solution to my problem.

Although I'm no expert at Vor I thought I was making progress of understanding it. First off I will state how I use the Vor normally and it does usually work.

I take off and fly Vor to Vor using the cessna 172 until I reach my final destination. I input the required Vor frequency into the Nav 1 radio then press the standby button. The DME shows how many miles I am from the station and my Vor needle moves. I use the OBS to centre the needle then fly the heading keeping the needle centred until I reach the required station. I usually do the process sucessfully from station to station however heres my problem......
I was flying a certain flight plan and made a note of the Vor frequencies as normal. I inputted the frequency into the nav 1 radio and as usual the DME showed how many miles I was from the station. However the needle on the Vor indicator did not respond as it usually does and I used the OBS to spin the dial, but still no responce. I decided to make a rough judgement by the flight planner map and fly in the direction of the vor and even really close the needle never responded.
Like I stated I am a novice, so has anyone got any idea of what might be doing wrong?

Regards