tmux Ctrl+B not working

I think this deserves a clear visible answer which is hidden in form of a comment under the first answer.

Assuming the default tmux configuration is being used, novice tmux users please follow the instructions below to split the pane

To split the pane horizontally

1. Press Ctrl+B
2. Release pressed keys in Step 1
3. Press "  (on many keyboards, this is Shift+')

To split the pane vertically

1. Press Ctrl+B
2. Release pressed keys in Step 1
3. Press %  (on many keyboards, this is Shift+5)

The articles I found and referenced below mention [CTRL B] + [%] or [CTRL B] + ["] or Ctrl+b " which implies that we have to press all the keys together but none mentions the important part of releasing the pressed Ctrl + whatever key before pressing the another key in sequence in the command to see the desired action.

• Tmux support arrives for Bash on Ubuntu on Windows
• tmux Tutorial - Split Terminal Windows Easily

This is what I use for my configuration and I have Ctrl+A as prefix key.

set -g prefix ^a
set -g terminal-overrides 'xterm*:smcup@:rmcup@'
unbind %
bind | split-window -h
bind - split-window -v
bind N break-pane
# Set status bar
set -g status-bg black
set -g status-fg white
# Highlight active window
set-window-option -g window-status-current-bg blue

# Set window notifications
setw -g monitor-activity on
set -g visual-activity on

# Automatically set window title
setw -g automatic-rename

Test it by pressing Ctrl+A, then after that ?.