If you do not get any PTZ control on a 7 or 8 series DVR, please check the following.
On local DVR:
Please go to the PTZ menu and activate the 'Live PTZ' option for all channels that require PTZ.
On Web Browser:
Please log in to the web browser, enter the configuration menu. Under this menu you will see 'Camera Settings' in blue and a grey sub category of 'Permissions'. Under permissions you can select the 'Network Video Permissions'. These effect what can be done from the network browser. I advise setting the channels with PTZ camera's to 'Administrator'.