adding Notes to account gives error in CRM 2015 online

Hi,

While adding notes to account entity it gives business process error message as: You are not allowed to create notes for this account. I am getting this error for System administrator role also for account entity. Whereas i am sucessfully able to Notes to Contact and Lead opportunity. Not sure what exactly needs to be check for this as all the permission are there for system administrator role.

Thanks,

Ashok