Where is the next book? Do you know where I can find it?

Hey, um, I read this book called Elvenborn. It is the third book in a series called the Elvenbane Chronicles. I have read three of the books. The first is Elvenbane, the second is Elvenblood, and the third is Elvenborn.

I have been looking for the fourth book, because it is obviously not over yet, and I don't think that it will be over in the fourth book either. Well, I have been trying to find the fourth book--since the fourth book was published in 2002. They are written by Mercedes Lackey and Andre Norton. I have looked everywhere and I can't find it!

Help me! Please!?

Thanks. I think that the "Elvenborn" I have is a re-issue. Thank you for clearing that up for me.