This is the first time I have used Silverstripe or PHP. I have Silverstripe installed on my local machine.

I am getting the following error message when I try to add a new member to either my Forum or administrator security groups:

[User Error] Object::__call() Method 'addtogroup' not found in class 'Form'

POST /silverstripe/admin/security/EditForm

Line 133 in C:\wamp\www\silverstripe\sapphire\core\Object.php.

In addition, the "Add Member" button at the bottom of the page does not work.

Has anyone seen this before or have any ideas?

Thanks.