After you create a template, you can clone it to a template. Templates are master copies of virtual machines that let you create ready-for-use virtual machines. You can make changes to the template, such as installing additional software in the guest operating system, while preserving the state of the original template.
Verify that you have the following privileges:
on the source template.
on the folder where the template is created.
on all datastores where the template is created.