I'm trying to save a mask of the posterior cingulate cortex, but every time I try I get the following error message: 

11-May-2020 21:01:25 | FATAL | wfu_pickatlas.m | MException thrown. Stack follows:
11-May-2020 21:01:25 | FATAL | validateParent | Line 0375: HAX must be a valid axes handle.
11-May-2020 21:01:25 | FATAL | imshow | Line 0270
11-May-2020 21:01:25 | FATAL | Update | Line 2546
11-May-2020 21:01:25 | FATAL | GenerateMask | Line 2452
11-May-2020 21:01:25 | FATAL | SaveMask | Line 2213
11-May-2020 21:01:25 | FATAL | cmdSaveMask_Callback | Line 1000
11-May-2020 21:01:25 | FATAL | wfu_pickatlas | Line 0110
11-May-2020 21:01:25 | FATAL | @(hObject,eventdata)wfu_pickatlas('cmdSaveMask_Callback',hObject,eventdata,guidata(hObject)) | Line 0000

I've tried saving it in multiple different location, but I get the same error message everytime. I'd appreciate any help I can get.

-Kyla