Homework. 0%

I thought homework turnout was measly when I gave it in Theatre Arts. Little did I know turnout is almost as bad in a major subject!
Stealing from a great teacher (and equally great friend) in our building, Ms. Pick, I have come up with a more effective way of holding the students accountable for their work. Here's the layout:
If a student misses 2 homeworks in the same week and DOES NOT stay after to make up those homeworks the same day they miss the second, they will get a phone call home alerting their parents.
You'd think that would increase the amount of HW turned in AND the amount of students staying after.
Not so!
Today I had 2 students stay after. That was 2 out of 10 students. 20%. I have to call 80% of the students. I have 73 students total. In 2 days, 20 of them (or about 25%) didn't have their homework either day. That doesn't include the students who have turned in only 1 of 2 homeworks this week. Let's see...30 kids. 41% have done only 1 homework this week. which means 50 students (well over half!) have done one or less homework this week. And it's only Tuesday.
Kudos to those kids that do their homework regularly. I will certainly reward them with a homework pass at the end of this week.
But what do I do about what I can only call a homework failure rate???
I'm at a loss.