I just calculated my FOC and it came out negative...is it supposed to be an absolute value or is there something terribly wrong??

I followed the instructions to a T...
balance point = 17 7/16
Total Length = 30 1/16
30 1/16 / 2 = 15 1/32
15 1/32 - 17 7/16 = -2 13/16
-2 13/16 / 30 1/16 = -8%

I am shooting aluminum XX78's (2317)
Shooting 68-70 lbs
100 grain FP's and BH's

Any help would be great!