=IF(ISERROR(F16-K16),"",IF(SUM(F16-K160),"",SUM(F16-K16)))

Cells F16 & K16 can either contain a "Null String" ("") or a number created
from another IF statement , from these 2 Cells I need another calculation,
if the error "#Value" is made I want it to be blank, If the number is 0, I
want it to be blank, but if it's a number I want it to appear.

Any help is greatly appreciated