You need to make sure the BATTERY WARNING light is working first, as this passes a live to the alternator from the ignition(when swithced on) to excite field windings so the alt produces current when turning(engine running).
If this is NOT working you will get no charge.
You can do a few tests, with the engine running but the IND(battery warning light wire) terminal OFF the rear of the alternator, check VOLTAGE at the main output of the alternator(large 13mm nut terminal), note the reading, now touch a LIVE onto the IND terminal where you took the THIN wire(normally blue) off of the rear of the altenator , the alternator will now start chanrging if all is well, if it does not alter or go above battery voltage that you had to start with the alternator is duff.
tabetha