Run time errors
Mulab is not really professional (foolproof). Sometimes errors appear in the command window because of your typos.
For instance it used to be (now corrected) that if you typed: Fit Range 1 1300, without having loaded any data set, it would complain that the indices exceeded the data array dimension. Normally it is sufficient to load data and try again. This error was noted and corrected but many similar ones are still there.
If an error persists and you are pretty sure you are not doing anything wrong, try quitting mulab and restarting (type mulab from the matlab prompt), or, better, exiting matlab. If you consistently find errors when you perform the same (correct) actions, please report to me (RDR)
For ISIS data make sure you have NeXus libraries installed.