there was an error opening the excel file

[#1]

I was unable to open an excel file in a script or when I tried to directly open it. 

I tried open data file --> all files --> open with excel wizard, but the excel wizard was never launched and I kept getting the error message. 

The file format is .xlsx and the file wasn't opened anywhere else. 

[#2]

You do not use the Excel Wizard in JSL.  What you do, is run interactively once, and then go to the Source entry in the data table that was created by the Wizard, and copy the JSL from the Source entry.  You then use that JSL in your script to read in the Excel files.

[#3]

Question, is the file generated via an other program like Export of a SAP table? It could be that it's actually a XML file that Excel then can interpret even with the .xslx ending.

Try open the file in Excel and save it again. After that, try open it via JSL/JMP.

[#4]

Another posibility:
Sometimes Jmp cannot open an Excel file if the files is opened at the same time in Excel.