You keep saying that you "had it tested"..
Can you give us any figures on what was found?
Voltage across the batter terminals while running? While the charge light is on, and running?
You need to confirm that it is, or isn't, charging firstly. Believing those goons at parts stores is probably the second mistake you made. (the first being that you thought that they would know the answer)
Once you measure the voltage, and have specific numbers at hand, you can see where the fault is. either the reference wire for the light, or the charging system itself, etc.
Post what numbers you get when measuring as stated above, and I will be sure to keep an eye on this thread!
