How to always show IMAP groups

[Tang Yan]

Maybe it is another newbie question and I am so sorry.

First of all, problem background.
my gnus version: 5.10.6 downloaded from www.gnus.org .
And my gnus.el is as following(very simple again):
------------------------------------------
(setq user-mail-address "foo@bar.org"
user-full-name "foo")
(setq gnus-select-method '(nnimap "imap.bar.org"
(nnimap-server-port 143)
(nnimap-address "imap.bar.org")
(nnimap-stream network)
(nnimap-authenticator login)
))
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Suppose there is a new mail in my mailbox on the mail server.

Then, the problem is how to make the imap group always visible.
What I do is as following:
M-x gnus, I get something like:
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9: nndoc+gnus-help:gnus-help
*: nndraft:queue
*: nndraft:drafts
------------------------------------------
Follow instructions in "Installation, configuration and usage
instructions for nnimap".
Press `U', tab completion to subscribe `INBOX', and I get:
------------------------------------------
9: nndoc+gnus-help:gnus-help
*: nndraft:queue
*: nndraft:drafts
1: INBOX
------------------------------------------
What I want to do is to make `INBOX' group always visible.
Then I press `G c' and select `visible' and press `done'.
Then enter INBOX and read the new mail, and quit from reading mail
buffer to *group* buffer, and get the following screen:
------------------------------------------
9: nndoc+gnus-help:gnus-help
*: nndraft:queue
*: nndraft:drafts
0: INBOX
------------------------------------------
Then I send another mail from web to my mailbox, and wait for a while.
Press `g' in that *group* buffer, but I only get:
------------------------------------------
9: nndoc+gnus-help:gnus-help
------------------------------------------

Where is my subscribed imap group and why it is invisible?
Maybe I have done something wrong, if that, I am so sorry.

Should I press `g' in that *group* buffer to check new mail?
Or is there anybody who can tell me where to get help? Thank you.
I want to stick to gnus because i know i one day i will read news and
it is probably the best newsreader in the world, ;-). Just a little
hard for me, -_-b