What variety are they?

Packages passion flower seeds are generally dried out for long-term storage. This forces the seeds into dormancy (in my experience) and it's problematic to rouse them. I never intentionally dry my seeds, and in fact use stratification in moist sand to "prime" them for germination. I've had high rates of success.

Also, I've had more success planting seed in starter cups and not planting outside until the seedlings are 6" or more. The sprouts are tender and easily munched by insects that wouldn't touch an adult plant.

Jayme made a good point about the seeds being stored dry for a long time. You should soak them in a mild acidic solution for a couple days prior to planting. I use orange juice and I also start all my passiflora seeds in containers.