I am trying to join a data table to the attribute table of a shapefile. I have done all the necessary steps to makes sure it works: removed spaces, not use numbers in column headers, remove illegal characters etc. BUT still when I try to join the table, Arcmap is not reading the GEOID field that I am trying to use to join the two tables. I cannot see it listed in the fields to join. What could be the problem?
If the field has a different type in each table (short vs double; long vs string, etc), non-matching fields won't show up in the join dialog, so you have to make a new, type-matching field
Whenever I encounter this problem I check to see if there are any previous joins between the tables you are trying to join. Then, making sure they are of compatible field types.