Accessing and changing Custom Property through "prop()" in Custom UI Python

Coding Python Support
1

Does anybody happen to know how to access and change the Custom Property using “prop()” for purposes of editing using a custom UI within python?

These are the custom properties I wanted to change:
image

And I thought this python code would do the trick:

import bpy

class LayoutDemoPanel(bpy.types.Panel):
	"""Creates a Panel in the scene context of the properties editor"""
	bl_label = "Test"
	bl_category = "Panel"
	bl_space_type = 'VIEW_3D'
	bl_region_type = 'TOOLS'
	bl_context = 'posemode'

	def draw(self, context):
		layout = self.layout
		scene = context.scene
		ob = context.object

		row = layout.row(align=0)
		row.alignment = 'CENTER'
		col = row.column()
		#rna_item = context.space_data.pin_id
		col.prop(ob, "Arm_Left_FK/IK")

When I hit run script, there is no Slider Created to allow me to change the property from within my custom-made User Interface. So once again, any idea on how the custom property can be accessed using “prop()” within python? Thanks!