I have instructions as to how to change settings in order to use a tax return form, which can be viewed here http://www.hmrc.gov.uk/ct/ct-online/file-return/online-change-settings.pdf. I can follow them succesfully up until step six. The "Add to Trusted Identities" button is greyed out and can't be pressed. Also, the current settings are different from the ones shown on the instructions - the fourth option has a tick instead of a cross (not sure if this is important but might tell you something...)
I have tried opening the file in Reader under admin but this made no difference, and I have checked that I have a compatible version of Reader (I have 9.3.0). How can I either make the button clickable or do the steps after 6 by a different method?