How to invite Chinese for a American's birthday party?

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Hello, every body.
i am a American people who working in China for 5 months, i had sent invitation to all my Chinese collegues to join my birthday party 1 week in advance. today is my birthday, till now there is nobody comes, nor i receive any message that they will come or not.

do you know how should i do to invite them to my birthday party? i would be more happy if they could come.

Thank you!