bpy.ops.view3d Runtime Error

When I run:

bpy.ops.view3d.snap_cursor_to_center()

or

bpy.ops.view3d.snap_selected_to_cursor(use_offset=False)

in Text Editor as Script I got a RuntimeError in poll function of classmethod:

RuntimeError: Operator bpy.ops.view3d.snap_cursor_to_center.poll() failed, context is incorrect

I don’t exactly need it, because when I run script as operator from SPACE menu everything works fine. So I just want to understand blender basic paradigm. What does excatly means this error? I can’t run scripts with view3d functions in text editor as scripts, is it correct or it is a bug? I use 2.73 version of blender