Fitnesse with Sites

I'm trying to create my first Fitnesse test and having some issues with getting it to work.
Our appian system uses a combination of SAML and Native logins, which once the user logs in present him with a SITE as the default start page. A number of sites are available to either type of user.

I want to login with a Native account and switch from the default site , to one of the different ones , the eventual aim of interacting with the interface on siteB.

However I'm getting a cpl of issues.

When I login . if i simply use the URL then I don't get beyond the authentication options. If I edit the url to use ?signin=native I do get a successful login - however I see errors in the fitnesse window regarding a malformed url.- Can i ignore that error ?

When the default site a page opens - I'm not able to navigate to siteB. What seems to happen is that siteA loads, and then the profile drop down appears saying I'm logged in._as if the user has single clicked on his avatar icon)

If I try Navigate to Site then I get a null pointer exception. (below)

If I try Click on Site, then i just get An error has occurred: Site Page -SiteB

Null Pointer

__EXCEPTION__:java.lang.NullPointerException
	at com.appiancorp.ps.automatedtest.site.Site.navigateTo(Site.java:28) [fitnesse-for-appian-20.1.jar]
	at com.appiancorp.ps.automatedtest.fixture.SitesFixture.navigateToSite(SitesFixture.java:23) [fitnesse-for-appian-20.1.jar]
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) [rt.jar:1.8.0_202]
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) [rt.jar:1.8.0_202]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) [rt.jar:1.8.0_202]
	at java.lang.reflect.Method.invoke(Method.java:498) [rt.jar:1.8.0_202]
	at fitnesse.slim.fixtureInteraction.DefaultInteraction.methodInvoke(DefaultInteraction.java:81) [fitnesse-20160515-standalone.jar]
	at fitnesse.slim.MethodExecutor.callMethod(MethodExecutor.java:57) [fitnesse-20160515-standalone.jar]
	at fitnesse.slim.MethodExecutor.invokeMethod(MethodExecutor.java:38) [fitnesse-20160515-standalone.jar]
	at fitnesse.slim.MethodExecutor.findAndInvoke(MethodExecutor.java:72) [fitnesse-20160515-standalone.jar]
	at fitnesse.slim.FixtureMethodExecutor.execute(FixtureMethodExecutor.java:20) [fitnesse-20160515-standalone.jar]
	at fitnesse.slim.StatementExecutor.getMethodExecutionResult(StatementExecutor.java:135) [fitnesse-20160515-standalone.jar]
	at fitnesse.slim.StatementExecutor.call(StatementExecutor.java:108) [fitnesse-20160515-standalone.jar]
	at fitnesse.slim.instructions.CallInstruction.executeInternal(CallInstruction.java:35) [fitnesse-20160515-standalone.jar]
	at fitnesse.slim.instructions.Instruction.execute(Instruction.java:29) [fitnesse-20160515-standalone.jar]
	at fitnesse.slim.ListExecutor$Executive.executeStatement(ListExecutor.java:49) [fitnesse-20160515-standalone.jar]
	at fitnesse.slim.ListExecutor$Executive.executeStatements(ListExecutor.java:43) [fitnesse-20160515-standalone.jar]
	at fitnesse.slim.ListExecutor.execute(ListExecutor.java:85) [fitnesse-20160515-standalone.jar]
	at fitnesse.slim.SlimServer.executeInstructions(SlimServer.java:84) [fitnesse-20160515-standalone.jar]
	at fitnesse.slim.SlimServer.processOneSetOfInstructions(SlimServer.java:77) [fitnesse-20160515-standalone.jar]
	at fitnesse.slim.SlimServer.tryProcessInstructions(SlimServer.java:64) [fitnesse-20160515-standalone.jar]
	at fitnesse.slim.SlimServer.serve(SlimServer.java:49) [fitnesse-20160515-standalone.jar]
	at fitnesse.slim.SlimService.handle(SlimService.java:154) [fitnesse-20160515-standalone.jar]
	at fitnesse.slim.SlimService.acceptOne(SlimService.java:162) [fitnesse-20160515-standalone.jar]
	at fitnesse.slim.SlimService.accept(SlimService.java:124) [fitnesse-20160515-standalone.jar]
	at fitnesse.slim.SlimService.startWithFactory(SlimService.java:76) [fitnesse-20160515-standalone.jar]
	at fitnesse.slim.SlimService.main(SlimService.java:56) [fitnesse-20160515-standalone.jar]