Too cold for primed keg?

I kegged a batch of Irish Red ale about 5 weeks ago after 1 month in the primary (no secondary.) Instead of force carbonating I decided to prime the keg with sugar ( I used the same amount as I was directed to for bottling) and let it sit at "room temperature" for carbonation. After more than a month in the keg the beer still is flat. The keg is sealed because it's been holding pressure w/o being hooked up to the tank. I think the problem is from my "room temperature" being in the 50s for the first 2 weeks. Now that I've moved it to a warmer place I expected it to finally carb, but I don't seem to be getting anything.

I know that since I'm using a Keg I could crank up the pressure to the right PSI toss the keg in the fridge and let that do the work, but I don't want the sugar to make the beer too sweet. Should I add yeast (and if I do, what kind? grocery store?) or should I make the keg warmer and keep waiting?

ANY help would be great, I am really anxious to get this batch in my belly.

thank you.

Try shaking it up and keeping it around 75F. Most likely the yeast settled & went dormant. If that fails, get a packet of dry brewing yeast. Bread yeast bites for fermentation, but it MIGHT work for carbonation. It is bred for fast CO2 generation and eating simple sugars.

If you go that route, let us know how it works.

Thanks for the response. What would be too warm? The only Idea I have for warming it is to put a heat pad on it, I could monitor the temperature and take it off when it's too warm, but we just can't keep our apartment that warm (I'd like it but my wife would flip and neither of us would enjoy the electric bill.) Would more yeast be bad if there is still other yeast in there, or should I just add it to be safe?

Something else to look out for is the keg not sealing do to a gradual increase of pressure that happens from carbonating with priming sugar. I've got one keg that has to get hit with a blast of pressure or it will leak. This is probably not what is going on but something to consider.

I've hit it with about 30 lbs and then backed it off every time I do any testing of the beer. I also did a check for leaks when I first got the keg, but I guess I'll find out for sure if I end up force carbonating it later. Thanks though, I'll keep an eye out for that as a possibility.

50's is WAY too cold. 70 to 75 is what works best. Too high would be anything above 75.