Unexpected output for If formula containing isblank

I have a table with these results

F G H I
6 10.5 357 357 -5.68434E-14
7 1 34 34 2.84217E-14
8 1.5 51 51 0
9 0.5 17 17 1.42109E-14

From these formular:

F =IF(SMALL(IF(Profile!$A$2:$M$102=$M$6,ROW(Profile!$A$2:$M$102)-ROW(Profile!$A$2)+1,ROW(Profile!$M$102)+1),1)>102, "", INDEX(Profile!$A$2:$M$102, SMALL(IF(Profile!$A$2:$M$102=$M$6,ROW(Profile!$A$2:$M$102)-ROW(Profile!$A$2)+1,ROW(Profile!$M$102)+1),1),10))&""

G =IF(SMALL(IF(Profile!$A$2:$M$102=$M$6,ROW(Profile!$A$2:$M$102)-ROW(Profile!$A$2)+1,ROW(Profile!$M$102)+1),1)>102, "", INDEX(Profile!$A$2:$M$102, SMALL(IF(Profile!$A$2:$M$102=$M$6,ROW(Profile!$A$2:$M$102)-ROW(Profile!$A$2)+1,ROW(Profile!$M$102)+1),1),11))&""

H =IF(SUM((IF($O$29:$O$52="",FALSE,($O$29:$O$52)))*IF($A$29:$A$52="",FALSE, IF($A$29:$A$52=D6,1,0)))=0, "", (SUM((IF($O$29:$O$52="",FALSE,($O$29:$O$52)))*IF($A$29:$A$52="",FALSE, IF($A$29:$A$52=D6,1,0)))*24))

I =IF(ISBLANK(G6),"big", G6-H6)

WHY is column I giving me such wierd results??!?!?!