It's only an opinion, but I'd say that your beam, (or maybe your arms ) is bent.

I bought an imperial blue powder coated one off of ebay (got a 'great price, delivered' and swopped it over with the original on my car, with a view to getting it worked on for the toe and camber adjustment, a la' Adrenalin.
Didn't notice immediately, but my 'new' one gives;
On passenger side (uk) about 15 mins neg camber, and visible toe out.
On driver side, about 1' degree 7mins neg camber and measurable but not visible by eye toe out
Really pissed me off. If you hit the brakes like you need them, the tails trying to come round me. Bit of steering application and your alright, but would've liked it too brake straight like it used too...