Do you possibly owe taxes? Check line 50 - its possible if you made more money this year, you may not have had enough withholding and you might owe taxes instead of getting a refund. Also, if you can get a copy of your 2016 return, then the best thing to do is to compare them side by side and then it becomes easier to tell where the differences are so can narrow down what may have happened (and if it's correct or a mistake)
