I tried to ei file my taxes but they told me some one has already calmed her how do I find out who and what do I need to do?

Who would have her SSN? Your exhusband maybe? Do you have any sort of Court Order saying that you deduct the child each year or every other year?

This is a new consequence of e-filing. You can't know for sure who did it. It could just have been a mistake. So what you do is file manually (the old way) and let the IRS sort it out.

By the way, its always a good idea to browse the forums or use the search feature to see if your question has been asked by others. This question has been asked several times in this forum and you could have had your answer with posting.

In addition to what ScottGem said - if you are NOT the custodial parent (the parent with whom the child spent the majority of nights in 2009), then be sure to include the relevant court decree that allows you to do this. If you ARE the custodial parent, I recommend that you include a note with your paper return explaining this.