How can I stop my x-wife from claiming our child during even numbered years?

The court allows me to claim my child on my tax return in even number of years and I have done so. However, my x-wife lives with my child out of state and she files her taxes before I do and she claims him as well. The IRS has continued to fine me for the deduction the last 3 times I have claimed my child. My x-wife refuses to work with me on this issue and the IRS states they do not get involved in domestic matters even though I sent them a copy of the judgement stating I claim my child. I cannot afford to travel out of state and hire an out of state attorney to take her back to court. What can I do? I live in Texas and she lives in West Virginia