The linked status on the dashboard has a slight delay. The dashboard might state you are not linked although you have already accepted the YouTube invitation. If this is the case, give the tool up to two days to update. One way you can make sure if you are linked with us is by checking your YouTube features page. If it states you are partnered with us, then there is nothing to worry about.
Note that the even though there may be a delay in updating the dashboard with the current status of your partnership, this will not have any influence in your monetization or payments. Earnings are collected from the moment you accept the invitation on YouTube to join the network.