how do I claim child care for summer camp for my dependent child I don't claim as a dependant

My ex and I have a 50/50 custody and parenting time agreement, and our divorce agreement states that I claim my son as a dependent until he is 18, and my ex claims our daughter until our son is 19, at which time we start alternating who claims her (me first).  We both pay for both kids to attend summer day camp for the days that they are with each of us, so I'm wondering how I claim child care for the summer for my daughter who is 11, but is claimed as a dependent on my ex's taxes.  I am in the "child and dependent care credit" section, and it is really only allowing me to put down my son...who is 13, so I don't think I can claim his summer camp/child care expenses for last year.  Please advise.