由于Dim上的循环，InStr无法工作

I am slowly building off this code as I'd like to learn VBA for future use. The purpose of this part of my code is to see if one cell's value is contained inside another sheet in the same workbook's cell. If this is true then I would like to mark column 10 of the same row in Worksheets("FDSA") as "ok" and write nothing if it is not. I am slowly building off this code as I'd like