Disable value for autocomplete expansion

I am trying to disable "No results found". I mean the user cannot select "No Results". I tried itemDisabled for this, but it doesn't work. Do you want to help?

 <div class="form-group">
                        <label>From <span class="text-red">*</span></label>
                        <p:autoComplete id="Source" styleClass="form-control" 
                                    minQueryLength="0" value="#{bean.source}"
                                    tabindex="1" maxlength="20" var="it"
                                    itemLabel="#{it.name}" itemDisabled="#{bean.source eq 'No Results Found'}" converter="${gec}" itemValue="#{it}"
                                    completeMethod="#{bean.completeSourceLocation}" scrollHeight="150"> 
                          <p:ajax event="itemSelect" onsuccess="destfocus();"></p:ajax>
                        </p:autoComplete>
                        <p:watermark for="Source" value="Source" />
                      </div>