Did you accidentally block desktop notifications from Livechatoo when browser notification appeared ? Check this tutorial to allow them and enjoy all features of Livechatoo:)
1) Click on the document icon in the address bar.
2) Look for Notifications in Permissions section and set them to Always allowed on this site.
1) Right-click anywhere on the page and then select View Page Info
2) Move to Permissions section.
3) Look for Show Notifications field and set it to Allow.
1) Open Opera menu and then open the Settings, or just use hotkey Alt + P.
2) Go to Websites section.
3) Look for Notifications and then click on Manage exceptions…
4) In Hostname patterns find http://app.livechatoo.com:80. Then click on Block.
5) Allow notifications for http://app.livechatoo.com:80.
6) Confirm new settings by clicking on Done.