[Wordpress issuses] yxl136731 on "toggle box not showing, [toggle]/[toggle] not working"

I am trying to add the following code in my new post:
[toggle title="Text"]This is the details[/toggle]

when I preview the new post,
[toggle title="Text"]This is the details[/toggle]
is displayed in my post
instead of the following
Text

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why the code is not working like what I am expecting?
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this is happening in my account at http://www.wordpress.com
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Thanks for any tips and help......

The blog I need help with is utdelearningadmin.wordpress.com.

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forums.wordpress.com