The mAh rating can't be accurate or the self-discharge rate seems high (about one week of charge with a few uses during the week).
My original Canon battery lasts about 50% longer between recharges and still working great.
I might have forgotten the "empty" battery for a week before recharging it, so if the self-discharge was high as I think, this might have caused the battery to die.
For the cost, it did its job as spare battery. Quality Control are probably low for these cheap batteries, so we get what we pay for.