red iceburg lettuce

Where are you trying to germinate them?

not usually.
Yorkie asked for germination details, I think, because lettuce doesn't always germinate if it's hot eg in a greenhouse. Your's sound as if they should be ok, though 

Yes, I asked about germination in case you were putting them in a heated propagator or similar - but you're not.

Have other seeds done OK in this compost?

If so, I'd go back to the seed company and complain as matt said.