Go to where you have your server. Go to the mod in your addons folder. Go to "CS 1.6 Shop menu mod\lua\autorun\client" . Open "cl_buymenumod". Find this function in the text

hook.Add( "Think", "OpenDaGunMenu", function()
if input.IsKeyDown( KEY_F3 ) then

I've already changed the bind to "F3" but it used to be "B". Make sure the thing is capitalized and change nothing else with the function. This should work as it did for me and my server.