Kris Jenner shares birthday message to her son Rob via Instagram, but he's busy celebrating with his girl & her son

Rob's mother Kris Jenner shared a heartfelt message to him via Instagram today. On the other hand, Rob Kardashian spent the eve of his 29th birthday with girlfriend Blac Chyna and her three-year-old son King Cairo. Clearly having a blast, he hopped on some of the rides with his new family at Legoland, California. Anyone notice how Happy he looks now? Lol. See the photos after the cut...