Signs don't visually break

Hello,

I was playing some snapshots and I was placing signs. However, I placed it wrongly so I wanted to remove it. The break particles appear, but the sign visually doesnt disappear. Even if I put another sign over it, the old sign shows. I don't have the files on my PC, I have a few links:

http://prntscr.com/4cowzt
http://prntscr.com/4cox3l
http://prntscr.com/4cox5t
http://prntscr.com/4cox8u
http://prntscr.com/4coxan

PS: I'm in creative, F3. Excuse me for my possibly bad English, I'm 13 year old and Dutch.