Matching calculated column

I was recently able to join two tables (Table1 and Table2) by matching a calculated column (string) from Table1 to a normal string column in Table2.  The next day, I replace my data table, and I am now unable to match Table2 columns to any kind of calculated column from Table1!  The calculated column in Table1 is also matched to its corresponding column in Table2 via Manage Relations/Column Match.  What happened?  Thanks in advance.

(8) Answers