Compiling libxslt

[Shienarier]

When i try to compile libxslt i get the error message that libxml2 cannot be found. But i have libxml2 installed. I have even told the ./configure where the .so files are, but it still can't find them.
What is wrong? I don't remember the versions, but both are the latest stable.

Please don't answer: "You could get the binary", as i already know that.