If you charged them up and then load tested them it self defeats the point of testing them.
Do you start your truck after you charge the batteries? No... you start your truck after it's sat for awhile. So try letting them sit (not on concrete btw) for a few hours and then come back and put the load tester on them.
At least that's how I always tested mine, if the symptoms are that of a dead battery and the charging system is up to par.
2007.5 2500HD CC/SB LTZ
498 rwhp, 845 rwtq
DiamondEye 4", EFI Live by BobO, Edge Insight CTS, S&B Intake, Bilstein 5100 shocks, MOOG idler/pitman with SS support, Raptor 150, P553207, !PCV, !EGR, Transgo Jr, Rare Parts tie rods, 55 watt 4.5k HID low/hi/fogs, Belltech 3" lowering shackle