Well, aeration could be the issue. Was the yeast viable (ie, did the smack pack swell)? I'm not a yeast guru, but I think I have read that 1968 is somewhat of a difficult strain. I'd give it another 24 hours and reevaluate. The only true way to know if fermentation is occurring is by gravity readings. There is the possibility that your equipment is malfunctioning and you cant "see" signs of fermentation.
A few things to consider next time...
- Make a starter...a yeast starter is a money maker for fast fermentation and avoiding stalled fermentation.
- Aerate the hell out of your wort...by any means. I pour the *hit out of my wort many times between brew kettle and bucket.