Catalysis of the reaction: D-glucuronyl-1,3-beta-D-galactosylproteoglycan + UDP-N-acetylgalactosamine = N-acetyl-D-galactosaminyl-1,4-beta-D-glucuronyl-1,3-beta-D-galactosylproteoglycan + UDP.
UDP-N-acetyl-D-galactosamine:D-glucuronyl-1,3-beta-D-galactosyl-proteoglycan beta-1,4-N-acetylgalactosaminyltransferase activity