Unchecking the Shared toolbar did not work for me. I followed Maarten van den Hoven suggestion and on the other instance it worked well. So after testing alot i found the problem.
In my case i am using a ASPX + Portal Page template which looks like:
<asp:Content ID="Content1" ContentPlaceHolderID="ContentPlaceHolderMain" runat="Server">
<cms:CMSPagePlaceholder ID="plcZones" runat="server"
First i thought the webpart IDs are unique because i checked all web parts and also i checked the web parts configuration displayed at the "Template" section.
This was my mistake!
I was able to slove the problem with the
ClientIDMode attribute for the CMSPagePlaceHolder.
<cms:CMSPagePlaceholder ID="plcZones" runat="server" ClientIDMode="AutoID">
Now its working.
Thanks for your time.