Check the removable bed surface to make sure it's properly positioned. It should be flat on all the edges, and flush with the sides of the plate.
If the build plate is all the way at the bottom of the printer, manually move it up to around the center.
From the Control screen on the printer, click the "Up 10" button underneath "Bed". You'll get a warning about the printer not being homed, but the bed will still move up. Continue to do this until it's about halfway up, and try again.