Cause
Label components can contain only alphanumeric characters, blanks, and underscores.
Label components can contain only alphanumeric characters, blanks, and underscores.
Correct syntax of the label component.
Try the following links for this error:
http://docs.oracle.com/cd/E16655_01/server.121/e26079/e12400.htm
https://community.oracle.com/message/2118177
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