Must I file form 2441?

I contribute to the dependent care flexible spending account at my employer, and they list the amount in box 10 of the W2 form. We were reimbursed for most of the daycare expenses we incurred. When I completed form 2441, it indicated we would get taxed on the amount we were reimbursed since my spouse doesn't work. Since form 2441 is for those who want to get reimbursed for their dependent care expenses, it doesn't say anywhere that I HAVE to file form 2441 - if I don't, they presumably would not tax me on ANY of the expenses. I want to do what they expect me to, which I expect would be to tell them what I should be taxed for by filing 2441. Advice?