Google Apps SAML setup

I am trying to setup Google apps to federate to my F5 as an IDP.

I have followed the iapp and also done this manually. I have other working SAML configs so think I understand the steps required.

Using the iapp the f5 presents a blank webtop initially as the saml resource is set to present on webtop/false. If I allow this onto the webtop the link works fine so I know the settings are all correct.

As per other setups I do not want a webtop, user browses to the SP, is redirected to F5 (idp) for authentication and then seamlessly redirected back to the SP (ACS).

Any ideas why I cannot get this to just redirect back to Google and not present a webtop?