Airbrush question

Another airbrush question:
Finally used my airbrush with the compressor and moister trap just now on a gundam model. I did a mix of 50 50 of water and paint. Here is the problem: the paint was really watery and there was a lot of spotting. So much spotting that I hardly got any coverage. I was using the specially made paint by Vallejo for airbrushing that is pretty thinned out already. A part of me says that I thinned it out to much or I should use it straight from the bottle. When I use other normal paints on my airbrush, there isn’t any problem.

I think you thinned it too much but I don’t use water to thin my paints. I use alcohol for acrylic paints.

Vallejo Model Air is pre-thinned already so you shouldn’t have to thin it anymore. I also heard it’s best to use their brand of airbrush thinner, should you have a need to thin.