If you ordered the Adorama brand paper, it is possible that you recevied paper that was manufactured by Ilford but that is not Ilford MGRC. Adorama may have paper made at the Ilford plant that's not the same specification as the Ilford MGRC. Adorama isn't in the paper manufacturing business, and someone is coating this paper for them. If you asked "Is this paper made by Ilford?" referring to the Adorama paper, it's very possible you got an honest, positive answer from someone. If you asked, "Is this paper Ilford MGRC?", then the answer probably should have been "No." In situations like this, it's rare to find a manufacturer who will admit that they make stuff for "house brands"...they don't want the confusion between their own product and other stuff they make to different standards for distribution in house-brand packaging.
I picked up a box of Adorama-branded warmtone VC fiber paper a while back when I was placing an order. It was an impulse buy for me...the stuff was so cheap that I figured I'd give it a shot. It definately isn't Ilford Warmtone MGFB (Ilford's designation for their current warmtone fiber paper). Having said that, it also isn't a bad paper. It's slower than Ilford MGFB, but it also tones a lot more easily than the Ilford-branded paper. I had to do some testing to get a handle on it, but once done I've been getting extremely nice images on it. It's a great paper if you want fiber paper that takes tone easily.
I have no idea who makes it, and if I ever buy another box I'll do the whole testing routine again because these house brands tend to come from the lowest bidder and therefore it might be a totally different paper next time. (Let me put it this way: If you bought paint from a major department store ten years ago and bought more of it yesterday, chances are that it was made by two different companies. Department stores don't manufacture paint, they buy paint from paint companies and have their label stuck on it. Is it the same stuff as the manufacturer-branded paint? Probably not. Is it bad? Who knows? You pay your money and you take your chances.)
This, by the way, is one of the advantages of sticking with a major brand name for things like paper and film. The major players tend to tell you when they're changing something. Kodak makes an announcement every time they switch a manufacturing site for a film or paper...just in case it changes the base product. On house-branded merchandise, there are no such guarantees. For example, the box of Adorama paper I have right now might be coated at an Ilford plant to different specifications than the Ilford-branded papers...next time, it might be from an Agfa plant. I can guarantee you that the shop is not in a big hurry to tell you that the paper you're buying isn't the same as a major brand, nor do they want to admit that they purchase their paper from the lowest bidder.
Anyhow...a lot of rambling there...if you ordered Ilford paper and got a black box, then something is wrong and you should send the paper back. If, on the other hand, you ordered Adorama paper under the assurance that it was manufactured by Ilford, what you have might actually be correct...but not what you thought you were getting...a simple misunderstanding. If, on the third hand, you ordered Adorama brand having been told it was the same stuff as Ilford MGRC, then you were probably misinformed and should make arrangements to return the paper.