“Say something 7 times and half of your people will say they’ve heard it once.”

That’s a Mark Horstman (of Manager Tools) quote.

And it doesn’t mean they aren’t trying. If it’s anybody’s fault, it’s probably yours. Maybe you’re boring. Maybe you’re not being clear. Maybe you didn’t make them feel heard first, so they weren’t ready to listen. Maybe you’re saying something they don’t want to hear, so you need to find a stronger way to say it.

Whatever the reason, never underestimate people’s ability to not hear you. And don’t blame them for it, blame yourself.