I am traveling from DSM to CUR.

When I searched Skyscanner, Google Flights and Kayak they could not find a routing that I found searching legs on my own.

I have two related questions:
1) Why didn't the search engines find the flight. It found some that were shorter and some that were longer. My only guess, is that the search engines didn't consider these flights/connections because the layover in CLT was only 1.25 hours--is that not enough time to change planes?
2) Since this route was not found as a single ticket, it sounds like my luggage won't be checked through to my final destination. Is that correct? Is there a way to get the luggage checked through on AA?

Thanks

Sorry if this is posted in the wrong forum...