problem when inheriting gwt-tk library

[dwi]

dear all,

i try to inheriting gwt-tk libray, here is my gwt.xml file :

<inherits name="com.google.gwt.user.User" />
<inherits name="com.google.gwt.i18n.I18N" />
<inherits name="asquare.gwt.tk.CPopupPanel"/>

<entry-point class="gov.miti.ris.gwt.client.Main" />

but then, i have compiling error :
[java] [ERROR] Unable to find 'asquare/gwt/tk/CPopupPanel.gwt.xml' on
your
classpath; could be a typo, or maybe you forgot to include a classpath
entry for
source?

could anyone help me to solve this problem...

thx,
dwi