Unable to see text in Unit Course


I have created a text block in unit course.

Then I copy text like this:

<periodic-rotating-file-handler name="FILE">
<match pattern="JBAS016200|JBAS010280|JBAS016300|JBAS011906|JBAS013101|JBAS015537"/>

<pattern-formatter pattern="%d{HH:mm:ss,SSS} %-5p [%c] (%t) %s%E%n"/>
<file relative-to="jboss.server.log.dir" path="server.log"/>
<suffix value=".yyyy-MM-dd"/>
<append value="true"/>

When I save it, I can see it in the web page but when I return to wisywing edtor in unit course, I can not see this text (but it is).

I think there 's an error with characters > and <.