Too Many Arguments

Too many arguments how would I fix that??

=IF(ISERROR((INDEX('Data Sheet'!$F$5:$BC$4000,MATCH(C4&D4,'Data Sheet'!$E$5:$E$4000,0),MATCH($G3,'Data Sheet'!$F$4:$IV$4,0))*1000000/(INDEX('Data Sheet'!$F$5:$BC$4000,MATCH(C4&E4,'Data Sheet'!$E$5:$E$4000,0),MATCH($G3,'Data Sheet'!$F$4:$IV$4,0))+INDEX('Data Sheet'!$G$5:$BC$4000,MATCH(C4&F4,'Data Sheet'!$E$5:$E$4000,0),MATCH($G3,'Data Sheet'!$F$4:$IV$4,0))/$AE$1))),"",MIN((INDEX('Data Sheet'!$F$5:$BC$4000,MATCH(C4&D4,'Data Sheet'!$E$5:$E$4000,0),MATCH($G3,'Data Sheet'!$F$4:$IV$4,0))*1000000/(INDEX('Data Sheet'!$F$5:$BC$4000,MATCH(C4&E4,'Data Sheet'!$E$5:$E$4000,0),MATCH($G3,'Data Sheet'!$F$4:$IV$4,0))+INDEX('Data Sheet'!$G$5:$BC$4000,MATCH(C4&F4,'Data Sheet'!$E$5:$E$4000,0),MATCH($G3,'Data Sheet'!$F$4:$IV$4,0))/$AE$1))),100%)

The syntax of your formula is

=IF( ISERROR( Some LongExpression ) )

It's nested incorrectly.

I won't try to parse the interior part, but it could be shorter and easier to mantain with some named ranges. Also, if you have Excel 2007 (or are willing to add a short macro), you might recast it in the form

=IFERROR( someExpression, defaultIfError)

Edit: I retract that first comment ... hold on.

It's a little easier to see in this form:

=IF(ISERROR( INDEX(Rng1, MATCH(C4&D4, Rng2, 0), MATCH($G3, Rng3, 0) ) * 1000000 / 
           ( INDEX(Rng1, MATCH(C4&E4, Rng2, 0), MATCH($G3, Rng3, 0) ) + 
             INDEX(Rng4, MATCH(C4&F4, Rng2, 0), MATCH($G3, Rng3, 0) ) ) / $AE$1), "",
       MIN( (INDEX(Rng1, MATCH(C4&D4, Rng2, 0), MATCH($G3, Rng3, 0) ) * 1000000 / 
            (INDEX(Rng1, MATCH(C4&E4, Rng2, 0), MATCH($G3, Rng3, 0) ) + 
             INDEX(Rng4, MATCH(C4&F4, Rng2, 0), MATCH($G3, Rng3, 0) ) ) / $AE$1), 100%) )

... which could be replaced with something that looks like this:

=IFERROR( MIN( 
   (INDEX(Rng1, MATCH(C4&D4, Rng2, 0), MATCH($G3, Rng3, 0) ) * 1000000 / 
   (INDEX(Rng1, MATCH(C4&E4, Rng2, 0), MATCH($G3, Rng3, 0) ) + 
    INDEX(Rng4, MATCH(C4&F4, Rng2, 0), MATCH($G3, Rng3, 0) ) ) / $AE$1), 100%), "" )