when I edit the cell they disappear and my formula display #value!

eg:

{=IF(SUM(IF(Tracking!$G$17:$G$9895="NB",
IF(Tracking!$P$17:$P$9895="X",1,0),0))0,
SUM(IF(Tracking!$G$17:$G$9895="NB",
IF(Tracking!$P$17:$P$9895="X",1,0),0)),"")}