If I go on
Content Management > Content I cannot see any type-name of the tellafriend-form.

And then, if I klick on > Operation (German language = »Bearbeiten«)
I get that massage:

warning: call_user_func_array() [function.call-user-func-array]: First argument is expected to be a valid callback, 'tellafriend_node_node_form' was given in /includes/form.inc on line 366.