when you say "element for a viewscheme", which element do you have in mind? Thumbnail text?
Mid() would only work correctly if the path, and 'albumname' were always the same length.
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I suggest: (assuming you would like to keep the default [album] data already present)
If albumname is not derived from a field in your database, then create a new custom field.
tools > options > library > add. Call it what you like, albumname perhaps?
leave everything else at their defaults for now and click the OK button.
Next, select a couple of photos, then,
right click > library tools > fill properties from filename. In the directory field, type [albumname], (or whatever you called your new field, without the comma), untick the filename field, and hit OK.
Next, right click on any file on view, choose customise current view, place [albumname] in the thumbnail text area, hit OK. If that's what you want, select all the files and repeat the fill properties step above.
If that's not what you want, could you be a bit more specific?