I had similar problems when using liquid yeast for the first time.
I just poured the vile into my .1070 brew, and moved it into my 60-degree basement.
24 hours later, no activity.
I think I made 3 mistakes:
1- I should have made a starter, despite instructions on tube.
2- Higher gravity brews need more yeast regardless
3- A chilly basement is not the best place to start fermentation.
Fortunetly, by hour 30, it was cruising right along at normal speed. Though lesson learned.