1. Actor B, who is at the height of his career right now, has reportedly caught the celebrity disease. B was a star in a very popular drama recently and has been rising as a bluechip in the CF world thanks to the love of his fans. The problem lies in his difference in attitude. Usually known for his refreshing personality, he's maintained a positive relationship with broadcasting officials until he recently threw a fit in while at a private recording for a music program. He had asked if the show could go out of their way to make it public specifically for him, which producers could not comply with. In the end, he threw a fit with them. 

SOURCE: http://netizenbuzz.blogspot.kr/2013/01/rumor-mill-off-record.html

Why did Song Joong Ki not appear on Yoo Hee Yeol's Sketchbook?

It was later revealed that actor Song Joong Ki’s plan to appear in the Christmas special feature for KBS 2’s Yoo Hee Yeol’s Sketchbook was canceled.

A representative in charge of KBS variety programs told Starnews on January 3, “While we were negotiating about Song’s appearance for the shooting, we couldn’t reach an agreement about having people in the audience. The show was originally planning on an event that grants singers’ wish without audience, but Song Joong Ki had a different idea. He wanted people in the audience.”

The shooting for the special Christmas feature of Yoo Hee Yeol’s Sketchbook took place on December 11 at new KBS building in Yeouido, and when the news about Song’s appearance broke out, it drew much attention from public.

The representative continued, “At that time, we were taken aback because we were in the middle of negotiating a deal and nothing was decided for sure. You know, when you are doing business like this, we succeed or fail to cast certain stars. Song was one of those cases when the news broke out."

SOURCE: http://en.korea.com/blog/enter/tv/why-did-song-joong-ki-not-appear-on-yoo-hee-yeols-sketchbook/