Hey
Could you provide a little more background?
- Is this a new site?
- has it previously ranked in Google AND Bing
- ranking for what and in what position?
- Has anything on the site changed radically recently?
I can see it is indexed in bing and often ranking in one engine usually is pretty close to another so it is likely just a case of waiting a while. I tend to think Bing is a little more old fashioned in it's approach to links and sensitive to traditional on page signals whilst Google has become more nuanced.
In all likelihood, it is just a matter of time but if you can give a bit more info I am sure folks will offer some advice.
Cheers
Marcus