Originally Posted by tommytomtom
I just tried to install the new JBpatch jbpatch_3.1.0_fw510.zip however that did not work either. So I have a problem that is not related to this thread and I'll open another one!
Some versions of Duokan just gray out the "Update Your Kindle" button. You could either uninstall Duokan temporarily or put an empty file named "DUOKAN_DISABLE" in your kindle root and restart your kindle before installing KPVBooklet. Don't forget to remove the "DUOKAN_DISABLE" file if you want to switch to Duokan again.