[MiqsPix]

I have a Nissin Di622 speedlight flash on my Canon 1000d but cannot get consistent inside house portrait flash results. Some are overexposed, some are under. I know if I use the auto setting all will probably be ok but I am trying to learn by using either aperture priority, shutter priority or manual set up, whichever is the best. I have selected all the respective settings on the camera e.g. portrait, external flash, and tried flash exposure compensation but still cannot get consistently what I want. Some are great, some are awful! Unfortunately I haven't got any LCD screen or distance readings on the back of my speedlight so I can't work it out as suggested. Is there any way I can be more successful with flash using the Nissin Di622?

Edit:
I now realise I wasn't using the E-TTL II Evaluative flash mode setting. I now have more consistent results. Unfortunately I want to use ISO 200 to reduce noise and keep quality and when I set this I get the aperture setting flashes in my viewfinder. Something is obviously wrong! I want to use an exposure with flash of 60-125th sec with an ISO of 200, as my younger subjects move. Can this be done?