how do you aero ppl get %100?
take off the dome
It looks like a home made one.
Are your sprayer heads at the same height as the stems?
If they are under the stems they might not be getting wet.
I get 100% most of the time, the one ocassion it didn't work well was when the cuttings came from a very unhealthy mother. If you give more info on temps, humidity etc. I'm sure someone will be able to sort your problem out.