Because the batteries have not been used for two years the plates in the batteries have more than likely sulfated which makes them hard to impossible to recharge. Idle batteries whether they be 6v auto type batteries or industrial type need to be charged at least every 6 mos (every 90 days is ideal).
Some times you can get them to recharge by putting them on a a "equalize" charge cycle (a slow charge rate for a long period of time maybe 12-16 hours). If that doesn't work you'll need to replace them.
You didn't mention how old the batteries were or if you needed to add water to the batteries to cover the plates before charging. If the cells are dry then they won't charge. Add just enough to cover teh the top of teh plates. Then add more (to about 1/2" below the fill hole.

Good luck.