New EXIF ​​Tags Always "Unknown Tag"

Question

This is how I add some custom EXIF ​​tags to the image:

PropertyItem propItem = file.PropertyItems[0];
propItem.Id = //ID
propItem.Type = 2;
propItem.Value = //Value
propItem.Len = //Length
file.SetPropertyItem(propItem);

An example can be found here.

But the tag has no name:

How to add a name in PropertyItem?