Your loadedImage array is local to the loadPics() function and will disappear as soon as the function ends...
I suppose you have another loadedImage array declared at the global level, shadowed by the local declaration in the function.

Does a change to:

loadedImage[i]=loadImage((i)+".png");  fix it?

I though it was that to begin with PhiLho but the brackets indicate drawing is within the method....

1.
please post your whole sketch and not just one function.


2.
please have this line before setup(), not in loadPics() :

1.  PImage[] loadedImage = new PImage[20];

3.
please in line 13 don't write

1.   }  // end void

because void is only the return value (none).

Write

1.   }  // end function

I like the expression late night coding...