pannel lining with Tamiya Acrylics?

I don't use Model Master lacquer, but since you call it a lacquer, it may be an alcohol solvent system. Tamiya acrylics are an alcohol solvent system as well, which explains the problem. Use an enamel or non-alcohol soluble lacquer for your barrier coat.

I just tried doing the wash over the enamel paint itself, and it stained too...

How are you mixing the acrylics for your wash? I don't wash with acrylics, but my understanding is that the general rule of thumb for acrylic washes is to thin to about 10% paint, 90% water and a couple of drops of dishwashing detergent to (a) reduce the surface tension so that it flows easily and (b) break the adhesion of the paint so it can be removed easily. Go light with your wash as it's easier to add more than it is to remove it when you use too much.

 

There is maybe a bit more paint then 10% but theres ALOT more water.  no dish detergent though, last time it just made bubbles...

Is the surface smooth, as in almost glossy?  Washes do not work well on flat surfaces, they cause the stains you are referring to.  I normally use flat paints but before a wash I spray several coats of Future, apply my washes, and then spray a couple of coats of clear flat to get the flat finish back.

Also, the dish detergent is important.  It reduces the surface tension of the wash and allows it to flow better.

Its staining a laquer GLOSS topcoat

Personally I would recomend using oils instead of acrylics, the are workable over a long time and staining can be wiped off easily. 

That aside, try add a few drops of soap to the wash, stir slowly to avoid bubbles. with a gloss surface and the right amount of soap it will be easy to remove the ''staining''.   

Experiment on something first to get the right soap ratio.

I have used alcohole to remove minor acryl stains but be carefull.

If nothing worked do this: instead, then go to bed and wait for another answer