Missed Schedule Problems

have you setup your timezone in settings->general

Yes I have.

is your post has never been published or after some time has it been published

Sorry, but I don’t understand what you’re saying or asking.

try switching from your theme to twenty eleven theme if the problem persist after that also than the problem is with wp-includes

You said: “if the problem persist after that also than the problem is with wp-includes”

What is: “wp-includes”?