URL Found for Word .htm but not for Excel .htm

Thanks in advance for any assistance!

I am new to DW and am encountering an issue uploading a .htm file created from an Excel sheet to my office's web page. 

The functional old method: information was saved as a Word doc, re-saved as a .htm file that overwrote the previous day's .htm file, and then drag and dropped into WinSCP over the .htm file that feeds our web page. Word documents continue to transfer to .htm, to the remote server, and onto the web page as anticipated, regardless of what the Word doc contains.

The non-funtional new method: the entry of the same data now requires an Excel spreadsheet. I can resave the Excel sheet as the same .htm file, and prior to uploading, I can get the Excel web page to open on its own in Explorer as desired. When I drag and drop the same .htm file over to the WinSCP server (?), it indicates that the file has indeed been replaced. However, unlike the Word doc that then spits the text to our web page, the replaced Excel file only generates a "The requested URL was not found on this server." error onto the web page.

Given that I'm dragging and dropping the exact same .htm file from the same drives and into the same locations, I'm assuming the error has something to do with how how .htm files are formatted differently between Excel and Windows data? Anyone have any insight into what's going on or how I might get DW to import an Excel-based .htm file on to our web page?