To create ETL

I want to get a new etl by connecting two datasets. All stages are working, but they do not pass to the output part. When I press the save button, it does not save my work.

Also, I was able to combine a data set and a file that was on my computer before using the "join data" command. Now this option is not active. I cannot add the excel file on my computer to the domo. Is there a system problem?