[Acts 2:34 NKJV](http://www.biblegateway.com/passage/?search=Acts%202:34&version=NKJV):

> 
> “For David did not ascend into the heavens, but he says himself: ‘ The
>  LORD said to my Lord,“ Sit at My right
> 
> 
> 

Why didn't David ascend to heaven? Is this past tense? Is David in heaven now, or has he just never ascended into heaven all at?