A:
What problems are you having with the mount? The only thing that I can possibly determine is that the VESA pattern of your TV (200x300mm) do not align with the TV mount VESA Patterns that it supports:
Supports a variety of VESA patterns
Including 100 x 100, 200 x 100, 200 x 200, 300 x 200, 300 x 300 and 400 x 300.
You may have to purchase a different TV mount.