If you cannot use your fixed phrase, these reasons below are considered.
・The box [Replace sentences entering] is empty.
・[:] is full width
The box [Replace sentences entering] is empty
In order to [Replace sentences entering] in [Manage fixed phrase], the box needs to be checked. Here is how you can set and check.
(1)Click the setting button on the upper right of the management page. 
(2)Click [Manage
fixed phrase] on the left side of the screen. 
(3)In the section "Option", check in the box "Replace sentences entering". 
(4)Click [Update]
[:] is full width
When using fixed phrase during the chat, you need to enter [:] and alphabets in half width. If you enter it in full width, it would not function.