You are cionstantly overwriting the previously created textfield due to using the wrong depth definer. You are pointing to "this" to get a depth value, but planting it inside "mc", so it is always going to the same depth since "this" 's depth index doesn't change. Use...
mc.createTextField("textBoxes" + i, mc.getNextHighestDepth(), 0, leading, 200, 200)
That worked. Thanks for the help!