How many rows and columns are in your worksheet? You may have rows and/or columns at the bottom/to the right that look empty but Excel thinks they contain data. Open the workbook and press CTRL-END. That will bring the cursor to the bottom-right cell in the data. If it brings you to an empty row/column, then this is your issue and to resolve it, you have some choices:
1. Manually delete the empty rows/columns, save the file, and try again. The issue should be resolved.
2. If the issue is blank columns, and the columns containing data do not change, you can use the Data - OLEDB VBO to get the data into a collection using a SQL statement. That SQL statement should explicitly list the columns, rather than using * (since using * will also include those blank columns).
3. Using method #2 should also prevent the blank rows from being included, if you include selection criteria in the query (like for example WHERE AccountNumber <> "" or whatever works for your use case).