Refusal to take kids

I have a temporary order for custody. It has been in place for 3 1/2 yrs. My ex is now refusing to take the kids in July on a weekend that is his. Can he do this? I am not able to keep them, due to work. Besides, he never asked…just wrote an email that he will not be taking them.
I find this odd that he can do this. In this case, I want to send them up to another state with my parents for a visit. Can I just do it and not give him his days?? I am considering doing this at the time he is refusing to take them, that way I have someone who can watch them. Can I get into trouble for this? Basically, they would be in a different state for 2 weeks visiting my family while I am not there except for one of the weeks. If I don’t send them, I will not have childcare.

Yes, the court views visitation as a privilege and there is no recourse if he does not take advantage of the same. If he has said he will not be taking his visitation that weekend, you may make other arrangements for the children that weekend.