What could be causing this?

I just received an and filter for my Tamron 10 to 24 ultra wide Nikon lens
i like it, however all the pics i have taken with it have a bluish streak in them, some larger than others
what could be causing it?
i use bulb mode with it which is accompanies by rather high aperture settings, could that be it?

Well, to be honest with you, I don't know. Let me check with some other people and maybe they can give you a good answer.

By the way, what do you mean by a "rather high aperture"? Do you mean a high f-stop number or a large aperture? I have to assume you mean a high f-stop number for a smaller aperture so you can get your shutter speed slow with the and filter.

ADD: Are you using a variable and filter? I have been told they can sometimes cause this, and / or a cheap filter can also be the culprit. I think the problem will just have to be approached logically. If you never see such a thing WITHOUT the filter and see it only WITH the filter, it almost has to be the filter. And filters can cost from a few dollars to very expensive such as the Singh Ray and B-W filters. Do you get what you pay for? Your photos may be saying yes.

Yup! Steve has it right in his edit. I bought a cheap vari-ND filter from Hong Kong. I used it on a Sigma 10-20mm lens.

As I progressed the and strength the dreaded X appears. It's an interference pattern from the positioning of the rotating polarising filter against the fixed one (which is how these variable and are made). If you look the darker regions form an X across the frame.

I returned the filter but it can happen I believe even with more expensive brands. It's very much worse using the ultra wide angle lenses like my 10-20mm and your 10-24mm. It certainly was less obvious when I used it on my 18-200mm lens.

Edited to add - some test shots I did with mine;
- about 6 stops as I recall;

and an extreme example at about 8-10 stops I think;

The filter.