constraining tasks and connecting them
 

I'm new to OmniPlan (and Macs) and I'm trying to figure out how to connect 2 tasks for which the first task needs to happen 15 weeks before the second task (the second task has other relationships which determine its timing). I tried playing with connections with lead times, but that wasn't doing it for me...

Any help would be great!

Dependency connections with lead times sounds like the right way to do it, so could you provide more details about how it "wasn't doing it" for you?