I am using the following formula to create a unique list, typically I wont have a fixed reference point at the point B10 is reference and the formula works fine in these instances. However in this case B10 will be come B11 and so forth, the issue I'm having is the formula is creating a unique list of numbers but ignoring the fact that although the number is already list in column B it is not unique when you factor in the number referenced in B10.

I.E B10 has a number 1234 and C10 has returned the value of 1, however when it looks at B11 which has a value of 4567 it does not return the 1 that is unique based on both criteria but instead returns blank.

Can anyone help, I apologise if this is very clear.

{=IFERROR(INDEX('Source Data'!$N$2:$N$5000,MATCH(0,IF(B10='Source Data'!$M$2:$M$5500,COUNTIF($D$2:$D9,'Source Data'!$N$2:$N$5000),""),0)),"")}