How to use SHGetFileInfo with SHGFI_PIDL in python

I'm trying to retrieve file information (specifically info about the icon) using SHGetFileInfo. In reality, I don't have the full path of the file, I only have the pidl.

The following code returns (0L, (0, 0, 0, '', '')) and my question is why.

from win32com.shell import shell, shellcon
def get_info():
    desktop = shell.SHGetDesktopFolder()
    eaten, desktop_pidl, attr = desktop.ParseDisplayName(None, None, r"C:\Users\Ella\Desktop")
    return shell.SHGetFileInfo(desktop_pidl, 0, shellcon.SHGFI_PIDL | shellcon.SHGFI_SYSICONINDEX | shellcon.SHGFI_ICON | shellcon.SHGFI_DISPLAYNAME)

On the other hand, the code bellow does work for some reason (it uses full path instead of pidl):

from win32com.shell import shell, shellcon
def get_info2():
    return shell.SHGetFileInfo(r"C:\Users\Ella\Desktop", 0, shellcon.SHGFI_SYSICONINDEX | shellcon.SHGFI_ICON | shellcon.SHGFI_DISPLAYNAME)

Thanks!