Having trouble writing

Okay, does anybody also have this thing where you have like so many ideas and stuff but like when you actually sit down to write or draw, nothing comes to mind?? Like I'm into poetry and stuff and during the day while I'm busy I'll have some awesome ideas, but as soon as i actually get to write em down I just blank? 

I think I'm starting t understand why authors take a trip to the middle of nowhere to write a novel they'll never finish....