I am using Teams Power app
I have a text box, whose value property is as below, this is working fine,

But when I apply the same on default of combo box its giving me error

Items is based on collection, which is working, Default selected item I put
["INITIAL"]
This is working fine.
only default property it is not accepting. I am writing the same as of text, as due to that code, I can see the old records based on the selection of gallery.
Please guide, how to be written