Problems with mirroring!

Hi guys,

I'm having problems with mirroring my chair. I made half of it ready and all I need to do now is mirror it, to have the entire chair, but it says it has a problem with connecting the two parts! Only the seating part is going smoothly.

Can you please tell me what's wrong and help me to fix it! Thanks so much!

file: https://drive.google.com/folderview?id=0B-0a15UMJnHaUF9JX3VCelpFMnM&usp=sharing

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