I'm a newbie and have been struggling with refreshing the datasource to my dashboard.  I did search but couldn't any posting to this effect.

When I load the new data from a file of the same name, with a same named tab and all the same column names, I end up with a bunch of "F" columns, which seem to be unrecognized.  I have 3 files, 2 are stored copies of the data at the end of August and September; the third is a DATA_wwsSales.xlsx that is the file I have the dashboard pointed at.  I can save August to this file name and it works.  I save September and I get the F columns.  I've checked every name as mentioned and as you can see a snippet of below.  I've even taken a copy of the August file, deleted the data but left the headers and then "paste values" from September into the "August" file and saved that to DATA_wwsSales... and I still get the F columns.  I then do the same process for August and it works again. 

I should note that there is less rows but the same columns in the September files versus the August, that is the ONLY difference.

The following screenshots hopefully show what I explained above.  Any insight from the pool of gurus is greatly appreciated.  I have a meeting with our CEO next Tuesday and need to get this operational.  I don't want to have to rebuild it all.

The DATA_wwsSales files loaded with the data from August - it works:

I then switch the data in DATA_wwsSales to the September data:

And, I get the F columns ...

Yet if I scroll, my columns are there too:

I go back and open the two files next to eachother... even copy the headers of Aug up into Sept for easier compare and even setup an if statement... and they ALL MATCH!

I very much appreciate any pointers.  I'm so frustrated trying to understand/figure out what's going on here.