When i trying to install the module "Website : Scroll back to Top"

Odoo Server Error

Traceback (most recent call last):

File "/opt/openerp/http.py", line 643, in _handle_exception

return super(JsonRequest, self)._handle_exception(exception)

File "/opt/openerp/http.py", line 680, in dispatch

result = self._call_function(**self.params)

File "/opt/openerp/http.py", line 316, in _call_function

return checked_call(self.db, *args, **kwargs)

File "/opt/openerp/service/model.py", line 118, in wrapper

return f(dbname, *args, **kwargs)

File "/opt/openerp/http.py", line 309, in checked_call

result = self.endpoint(*a, **kw)

File "/opt/openerp/http.py", line 959, in __call__

return self.method(*args, **kw)

File "/opt/openerp/http.py", line 509, in response_wrap

response = f(*args, **kw)

File "/opt/addons/web/controllers/main.py", line 896, in call_button

action = self._call_kw(model, method, args, {})

File "/opt/addons/web/controllers/main.py", line 884, in _call_kw

return getattr(request.registry.get(model), method)(request.cr, request.uid, *args, **kwargs)

File "/opt/openerp/api.py", line 238, in wrapper

return old_api(self, *args, **kwargs)

File "/opt/openerp/addons/base/module/module.py", line 718, in install_from_urls

bck = backup(module_path, False)

File "/opt/openerp/addons/base/module/module.py", line 59, in backup

shutil.move(path, bck)

File "/usr/lib/python2.7/shutil.py", line 299, in move

copytree(src, real_dst, symlinks=True)

File "/usr/lib/python2.7/shutil.py", line 177, in copytree

os.makedirs(dst)

File "/usr/lib/python2.7/os.py", line 157, in makedirs

mkdir(name, mode)

OSError: [Errno 13] Permission denied: '/opt/addons/website_back2top~1'

Note : I am trying from apps (online) in my Amazon EC2 instance