File Validation Not Working

I am trying to create following rule

            array('attachment', 'file', 'types'=>'jpg, gif, png, pdf, jpeg', 'maxSize'=>1024 * 1024 * 2, 'tooLarge'=>'File has to be smaller than 2MB','wrongType'=>'Only jpg, gif, png, pdf, and jpeg filees are allowed.' , 'on'=>'create'),
            array('attachment', 'unsafe', 'on'=>'update'),

where attachment is a non db attribute, declared in model.

and in the controller

			$model->setAttributes($_POST['AgentAttachments']);
                        $model->agent_id=$this->_agent->agent_id;
                        $file=CUploadedFile::getInstance($model, 'attachment');
                        $model->attachment=$file;
                        $model->file_name=$model->attachment->name;
                        $model->extension=$model->attachment->extensionName;
                        $model->save();

I can attach any file type with any size, validation is not working.

Please help me identify the issue.