membership sign up error

Hi I have setup the membership plugin and have tested it out but when you try to signup the website goes to a blank page once you've filled in the registration details - I have granted support accesses requested on live chat - but the chat keeps cutting out so I thought it best to put in a ticket.

Also on my homepage for this site I have a priceless with signup buttons - is it possible to link each plan to the correct signup form so that you don't have to choose again when you get onto the registration page - just wondered if this was possible as it would streamline the signup

regards

Paul