Simple Attribute Join Error: "Resulting Table Has No Rows"

[GraceVan_Horn]

I'm attempting to do what I think is a very simple join, but for some reason I'm getting the error that "the join was successful however the resulting table has no rows." I'm trying to join based on a unique attribute, titled "FID" in both the original layer and the joining .csv file. Everything is formatted right in the joining .csv, I think - no blank rows or columns, no formatting at all, actually. What am I doing wrong?

[DanPatterson_Retired]

Try to convert the csv to a geodatabase table prior to doing the join to ensure that everything that could be done to produce an acceptable table has been done.

[GraceVan_Horn]

Thank you! I did that, but got the same result.  When I run the Join Validation (now using slightly different attribute titles - I was worried the FID was part of the error), I get the following response: "The number of matching records for the join: - No matches found by joining [GEOID] from <0> with [AFFGEOID] from <County_Designations.csv>.  I'm wondering if the problem is with the original layer, which is not named "0" - it's 2016_US_Counties. I'm attempting to do the join through that layer's attribute table, but is it possible it's not searching the right data from that layer? 

[DanPatterson_Retired]

sounds like we need to see a screen shot of the tables