Safety Stock indexing

Let me start by thanking everyone in advance. I am new to the forum and hate jumping on here to ask a question like this that has probably been answered several times over.

I have a worksheet that I am trying to build to help calculate Safety stock based off of a products ABC classification (on rev and quantity), as welll as, its coefficient of variation. I am having a couple problems that I hoped you may be able to help with.

First, in column CS I am getting #N/A errors on a vlookup for some of the records. I dont see what is going on because the value that I am looking up is also looked up off of another tab. Is this a metadata issue or am i missing something?

Next, in column DH I am trying to do an Index Match off of a reference table on tab labeled Explain! I am using the below formula, but some of the values it returns are good and some are not. Also, I am having #N/A values returned because I am matching off of the previously mentioned column CS for one axis of my reference table.

=INDEX(Explain!$B$15:$K$18,MATCH('CV trial'!DG4,Explain!$B$16:$B$18,0),MATCH('CV trial'!CS4,Explain!$C$15:$K$15,0))

Cheers