The error "External Table is not in Expected Format" could be from various reasons like:
1. Database is not connecting properly with the Excel file.
Below link can give you some workaround to fix this issue:
2. If you are using the same provideer for both type of Excels(xls, xlsx). You need to use different provider name for each.
For this, you can follow the below link:
Hope it will be helpful to you.
Pawan Awasthi(DNS MVM)
+91 8123489140 (whatsApp), +60 14365 1476(Malaysia)