When working with Excel files where each sheet isn’t just one table (i.e. the sheet contains multiple tables or there are unnecessary rows and columns above or to the sides of the table) you can use the Excel data connector "Define structure” option in Dundas BI.
You can provide a few settings to enable a direct connection to the specific data you need from the sheet.
In many cases, you would want to use the “Manual range” option and then provide the sheet name along with the Excel cell range in the format of the top left cell : bottom right cell and that will allow you to connect directly to that required table within your Excel sheet.