I have a problem with Loaddata command. I would like to load multiple folders from an other .pxp experiment. is it possible?
If you don't need to do this programmatically, simply use the Data Browser and the "Browse Expt..." option (drag and drop).
I wrote this code to load two folder from a selected file but it doesn't work (with a single folder it works...)

Function loadingfolders ()
String folderlist

As the documentation says, /S:

Specifies a sub-data folder within a packed experiment file to be loaded.

You can make two separate calls to LoadData.

It may be possible to do it in one call using /J but I'm not sure. It depends on the organization of your data. In that case you would omit /S or use /S to specify the parent of the data folders you want to load.

In Igor8, LoadData supports a /GREP that give you finer control over what is loaded. You probably don't need that in this case.