A few things to keep in mind if you're having issues pairing are these:
If your monitor is paired with the device itself (go into your device settings and bluetooth settings) then remove it, that can conflict with the connection.
If you have your monitor paired with any other apps other than the DDP Yoga app, disconnect it. That can also conflict with the connection.
Another thing that may help would be to connect the monitor when the DDP Yoga app starts scanning for one.