I think you can have too much vaseline on the cotton. Mine is definately greasy feeling but the cotton fibers are not completely matted down when I pull a ball apart. I think the loose thin fibers catch the spark then the more matted vaseline coated mass takes over to give a long burn time.

If yours was real cotton then either it was too matted or too coated. I have just never had this sort of tinder fail me, so give it another go for sure.

That knife was made by Nick Wheeler, and once again more information (as well as most of the above pictures) can be seen in an article at JM's Outdoors-Magazine.

http://outdoors-magazine.com/s_article.php?id_article=175

And welcome to the forum.