How do you figure you're "owed"?  This is not a PPS pool.  You aren't owed a damn thing until the pool finds a block, at which point you are paid for the number of shares you have at that time.  Hence PPLNS: paid per last N shares.  I don't know what the N window is here for Nexious, but your shares are only good for that time frame.  If a block hasn't been found within that N time frame, then those shares don't get paid.