I recently worked with a customer who needed to incorporate some Excel data into a report. Excel tables are not my first choice, but sometimes it is the only practical solution for the client. Since these were XLSX files we setup up an ODBC connection. But when we connected from Crystal we could not see any tables under that ODBC connection. We were thinking about re-saving it as an XLS when I did a quick online search and found the answer we needed in a forum post.
We had to go into File > Options > Database tab. Then under Tables and Views we had to add a check mark for ‘system tables’. Then the spreadsheet table showed up. I was surprised, because I have created many reports that read spreadsheets and I don’t ever remember having to do that. It is possible that there was something unique in that environment that required this change, but I never argue with success. And, if you ever run into something similar you have one more thing to check.