can't creating new setting of context

I created new context of the MODX(2.1.3-pl).
And, when I tried to create "Context Settings", it shows me the error message which is "Setting not found." I tried many times, but it still occurred the error.
How can I create new settings of context ?

Under is my methods.
1. right click on context and select "Edit context"
2. click "Context Settings" tab.
3. click "Create New" button.
4. full any blanks. (Key:site_start, Name:site_start, Value:21)
5. click "Save" button.
6. then occurred the error box " Setting not found. "

Thanks.

Make sure your cache_db setting is not enabled. There are some issues in the manager with this enabled in MODX 2.1 that requires you to clear the cache before certain changes are visible. Let us know if that is the issue.

Thank you for your comments.
It's sure that cache_db is No at System-System Settings.
Then After I cleared cache (Site-Clear Cache) , I tried to create new setting of context, but it occurred the error.

I dissolved it. If I used Japanese in context name, then the error occurred.

You might have a character set problem. Just in case, I would check the modx_context table and the fields in it in PhpMyAdmin to make sure the character set is the same one used in the Manager (specified in core/config/config.inc.php).