Embedding Excel files

This one might be for the Excel experts, but here’s my issue:

Here is my site: https://www.curtinflyingclub.com.au/

Here is the page with the link I’m trying to update: https://www.curtinflyingclub.com.au/?page_id=88

And here is the link on that page: https://www.curtinflyingclub.com.au/wp-content/uploads/2013/07/weightandbalance.html

It is an interactive weight and balance chart for aircraft loading.

I have a new Excel file (to update the one above) which I have converted to html.

The problem is, when I load it into WordPress, the link comes out as a static image – not the interactive page as per the link above.

I’m doing all this with a Mac (Excel 2011), so not sure if that makes a difference. I’ve searched everywhere for a solution and still can’t figure out what I’m doing wrong.

One interesting thing I have discovered is that to save the Exel file as a web page, the default extension is “.htm”

When I load the “.htm” file into WordPress, the page comes up as a 404.

However, if I manually type “l” on to the end of it (.html) after saving the file on my computer and then loading it, the page displays correctly. However, it still does not function as an Excel spreadsheet – it is just a static image.

I hope I am asking this in the right place. If this is not a Worpdress related issue then my apologies – perhaps someone could point me in the right direction?

Thanks, as always.