[Tutor] Tkinter iconbitmap question

[Phil]

I'm playing with an example from ttkbootstrap and I'm having a problem 
with the iconbitmap function. I realise that .ico files are not 
compatible with Linux so I've chosen an xbm file instead but I still 
have the same error as follows:

root = tb.Window(themename="superhero")

# root = Tk()
root.title("TTK Bootstrap! DateEntry")
root.iconbitmap('wind.xbm')
root.geometry('500x350')


Traceback (most recent call last):
   File
     root.iconbitmap('wind.xbm')
     ^^^^^^^^^^^^^^^^^^^^^^^^^^^
   File "/usr/lib/python3.11/tkinter/__init__.py", line 2136, in 
wm_iconbitmap
     return self.tk.call('wm', 'iconbitmap', self._w, bitmap)
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
_tkinter.TclError: bitmap "wind.xbm" not defined

Wind.xbm is in the same virtual environment directory as the python file.

I've searched the Internet for an answer and found the same question but 
no answers that makes much sense to me. It's not overly important. The 
desktop manager that I use doesn't have window icons, perhaps it's just 
an incompatibility problem?

-- 
Regards,
Phil