While it would be unusual if the defroster tab was still attached to the window and not making a good contact although we have seen repairs done with 'that other brand' which are non-conductive but well bonded to the defroster.
If you have a volt meter verify that the tabs are electrically connected to the defroster. Test directly on the metal base of the tab and on the defroster material next to the tab. With the defroster on you should see almost no change in voltage between the two test points at 12.5 volts or so (13.5 of so with the car running). There should be almost zero resistance between these two points.
Another way to test is the hot hand test. Turn on the defroster and then put your hand on the glass over the repaired tab. Be careful as this can get VERY hot if there is not a good electrical bond to the defroster.
If there is a sharp drop in voltage between the tab and the surface of the defroster this means there is a bad connection between these two critical parts. We like the Frost Fighter Tab Bonding Kit to bond these tabs back to the defroster because it is easy to use and is highly conductive. See www.frostfighter.com