Blogging Roller

Alex, who is six and who can read, has a little brother Linus, who is four and cannot read. This weekend Alex was asking about names. "Does Matthew have a U in it?" he asked. "What about Leo?" After asking about the presence of the letter U in all of his friend's names and finding that only brother Linus has a U, he went back to his room. Later that day, we noticed the following sign on his door:

no budey cum in if you do have a u in side yor name. go a way u names.

What have I done wrong!