Not able to edit or delete calendar events but able to add

I am a Site Collection administrator for a site. I have all the permissions. But when i tried to edit or delete events in Calendar, it doesnt work. Nothing happens when i click on Edit or Delete buttons.

I checked the Advanced Settings-> it also allows to do that

Create and Edit access:   Specify which items users are allowed to create and edit
	<input id="ctl00_PlaceHolderMain_ItemLevelSecuritySection_ctl09_RadWriteSecurityAll" name="ctl00$PlaceHolderMain$ItemLevelSecuritySection$ctl09$WriteSecurity" type="radio" value="1" /><label for="ctl00_PlaceHolderMain_ItemLevelSecuritySection_ctl09_RadWriteSecurityAll">Create and edit all items</label>

But surprisingly it allows to add new events....

What would be the problem... Am i missing some JS files? Or is it because some services or patches applied on Servers?