Rename a spot color (like HKS K) and print/export as pdf

Hi, I'm going mad about this.

I renamed a color to "WHITE" (in the palette editor), set it to be treated as a spot color and exported the document to pdf. No matter if I use "export to pdf" or print it with Acrobat, the color name in the pdf is always the original name... not WHITE as I named it.

What did I do wrong?