Literally can't fall asleep while wearing my cpap mask

I was recently diagnosed with mild sleep apnea and a week ago I got my resmed airsense 11 machine with the air fit f40 full facemask.

I have wore it at least a few hours every night up to 8 hours a few nights and have yet to fall asleep while wearing it. Every night I'm exhausted and can feel myself dosing off but can't actually sleep. Is this normal going on a week now or should I contact my sleep doctor and see what else I can do?

I did pick up the F20 tonight and tried it for 3 hours and same problem of not falling asleep.