Did he say why he couldn't do it? Is it that he can't or is that he won't??
I think you have given him plenty of warning, but like most men, he did not take heed (sorry to generalize chaps).
Has he phoned back yet?
I think you should stand your ground and tell him he needs to be there to look after his DD - but meanwhile have a contingency plan - does dd have a friend she could stay with - i know you feel she is too little, but it may be your only option and if she is with another little girl it may be easier.
I take it there are no family close by who could stay the night, rather than paying someone - and if you have to pay a childminder - get DD to pay it.