Have you tried taking a little match box, lining it with sandpaper, then putting your seeds in and shaking it for a few minutes? It scuffs up the outer shell so it germinates and opens easier.
Also with the colder temp. it may need a heating pad or put in a warmer location to germinate.
Here's just a total random theory I have as of lately, I'm wondering if large op growers have started irradiating their weed in an effort to steriliz the seeds. I've heard of people having all kinds of weird mutations from bag seed lately and really low germination rates. Weird eh?