Wavefront Obj Modification

In the export script for the wavefront .obj format is the code

            # Vert
            for v in me.verts:
                file.write('v %.6f %.6f %.6f
' % tuple(v.co))

I’m trying to add this code right before it to export the number of vertices but blender fails to load the script after I add the changes…

	    vertCount = 0
            for v in me.verts:
                vertCount += 1
	    file.write('vc %d
' % vertCount)

I’ve even commented out the code so only to set the variable vertCount = 0 and it still causes the script to not be read. Does anyone have any ideas as to why this doesn’t work?