its possible your adjusted gross income is too high
because of the advance credit that some got there should be a schedule 8812 in your return.
shorten version of schedule 8812 which is used to compute the credit (assumes certain other lines don't apply)
1) your adjusted gross income from line 11 of the 1040
2) number of dependents who are not under age 18 times $500
3) $400,000 if married filing jointly, otherwise $200,000
4) subtract 3) from 1) if zero or less use $0 otherwise round up to the nearest $1000 (for example $1,025 gets rounded to $2,000)
5) multiply 4) by 5%
6) subtract 5) from 2) if zero or less use $0 - (so for each $10,000 on 4) the credit is reduced by $500
