normally a drive can have no driveletter in two cases:
1. It is mounted as a folder on another NTFS volume.
2. It is not mounted
in your screenshot you can see the file with an opendialog control, so this code should work:
Delphi-Quellcode:
if OpenDialog1.execute then
begin
str_path:= ExpandFileName(OpenDialog1.FileName);
ShowMessage(str_path);
end;
see also ExpandUNCFileName