Setting Point Color Attributes Via Python Component

I am having some trouble modifying attributes on a point object from the python editor. All the back and forth between rhinoscript and rhino common has me a little lost I think. The following code produced an error when it gets to the 'ObjectColor': 

"Runtime error (ArgumentTypeException): expected RhinoDoc, got GrasshopperDocument"

import rhinoscriptsyntax as rs
import Rhino.Geometry as rg

def ptGrid():
    #define output grid as a list
    gridDimX = x
    gridDimY = x

    #loop to define X limits
    for i in range(gridDimX):
        #loop to define Y limits
        for j in range(gridDimY):

            #Create a point at i, j

            gridPt = rs.AddPoint( (i,j,0) )

            rs.ObjectColor(gridPt, [0,0,0])

            #Append Point to Output
            zero.append(gridPt)

Thanks in advance if you can steer me in the right direction!