I can see that in sidekick on geometrixx demo page. But in the pages created with my template, I can't see the ClientContext button. What did I miss?
This is becaue the geometrixx pages are built using a different template and your pages are using a different template.
To get ClientContext to show up on sidekick for your page, identify the template that your page is using and then from CRXDE go to that template location and check the sling:resourceType property value for the jcr:content node of the template. Once you identify the component that the template is using, go to that component and find a jsp that the component is using and add the below include to it -
<cq:include path="clientcontext" resourceType="cq/personalization/components/clientcontext"/>
Once done, the ClientContext button will show up on the sidekick for you page.