Hi,
Not looked at your code in detail, but a long time ago I did a blog post for XNA with a simple flag shader, hoping this might point you in the right direction 
You can find my old archived post here.
Hope it helps 
Hi,
Not looked at your code in detail, but a long time ago I did a blog post for XNA with a simple flag shader, hoping this might point you in the right direction
You can find my old archived post here.
Hope it helps