Using an IF statement with INDEX / MATCH

Hi all,

I have an INDEX / MATCH formula that is currently looking at a value and returning some corresponding text:

=IFERROR(INDEX('Data Converter'!$B$2:$T$5000,MATCH($L$17,'Data Converter'!$L$2:$L$5000,FALSE),4),"-")

I've now been asked to refine this to look at only data within the past 30 days. I've put this value in E6 and tried to use the following formula to look in only the specific dates (in column C):

=IFERROR(INDEX(IF('Data Converter'!$C$2:$C$5000>$E$6,'Data Converter'!$B$2:$T$5000,""),MATCH($L$17,'Data Converter'!$L$2:$L$5000,FALSE),4),"-")

...but this doesn't seem to work. I've also tried putting the IF statement beforehand:

=IF('Data Converter'!$C$2:$C$5000>$E$6,IFERROR(INDEX('Data Converter'!$B$2:$T$5000,MATCH($L$17,'Data Converter'!$L$2:$L$5000,FALSE),4),"-"),"")

...again no joy. I've tried running these as array formulas, but still nothing.

Can anyone suggest where I'm going wrong?

TIA,

FermentedR