Hey man, I've been giving it some thought, and my guess is that if there is a strong correlation between you giving out your schedule and them flaking you, it may be that you are giving them too much information... a bit of Mystery (pun intended) does magic with the ladies... so try some humorous answers such as:
- "I work one hour a month... when I go to the bank to cash my unemployment check"
- "I work mostly nights during the weekend... I'm a male stripper"
- "I have a flexible schedule, I'm a bounty hunter/pirate/... (something unbelievable)"
- "you are not a stalker, are you? I tell you when I work and then you make calls to my office and breathe heavily?"
You get it... either that or you need to experiment more so that the results are statistically relevant

good luck!