objective c - iOS : View works in ViewDidLoad but not once reloaded? -

i'm pretty confused problem. basically, have coreplot chart uses numbers i've parsed web.

the view works first time it's loaded i've since put reload button on it. reloading view this:

-(ibaction)refresh:(id)sender{       [self reloaded]; }  -(void)reloaded{....... lots of code } 

when click button, getting exc_bad_access error in plot code (the place making plot in coreplot.) here's line that's throwing error:

- (nsuinteger)numberofrecordsforplot:(cptplot *)plot {     return dates.count;  } 

i'm not sure why works @ first not once reload it. can please help? thanks!