PR4 Domain Checked? Weak PR Power?

Hey guys, I found a domain and it was PR4, it was checked and the bar was green so I guess it was real.
Anyway, when I checked it again - it says PR4, but it also says Weak PR Power, anyone have any ideas how can I fix this a bit or something like that? Or at least what does it "Exactly" mean?

Ignore PR it's not worth anything anymore.

bartosimpsonio said:

Ignore PR it's not worth anything anymore.

Click to expand...

What about generally flipping the site? Transforming it and then flipping?