How to properly set up context in plugins?

importing Digital Terrain Models using a python plugin

def register():<br/>
    bpy.utils.register_class(DTM) <br/>
    bpy.types.INFO_MT_mesh_add.append(add_to_menu)<br/>
<br/>
<br/>

i get the following. 

Error: Python script fail, look in the console for now...<br/>
C_dict, C_exec, C_undo = BPyOpsSubModOp._parse_args(args)<br/>
  File "C:\Program Files\Blender Foundation\Blender\2.67\scripts\modules\bpy\ops.py", line 142, in _parse_args
    raise ValueError("1-3 args execution context is supported")<br/>
ValueError: 1-3 args execution context is supported<br/>
<br/>