Setting messages to 'Read' doesn't work with icon

[nobody]

When I am looking at a folder with unread messages, 
at first login, using the star icon to set messages 
to 'read' and 'unread' will work.

Once I have opened a message and then returned to the 
folder, using the star icons will change the text to 
bold/unbold as though it had worked, but the unread 
message count remains unchanged, and upon returning 
to that folder, the unread message count is as it was 
before I changed it with the star icons.