Forum:Confused conserning anime episode one

I have lately finished watching the Deathnote anime and have noticed something

One of the Deathnote rules said "The Deathnote will be rendered useless if the victims name is misspelled four times"

Although i noticed that when light was testing the note the first time he wrote several spellings of the name Takuo Shibuimaru .... so why didnt the deathnote become useless?