Unable to establish PAM Trust

Hi,

Busy working through https://docs.microsoft.com/en-us/microsoft-identity-manager/pam/step-5-establish-trust-between-priv-corp-forests. 

Just got to the part where I need to establish the PAM Trust - everything thus far has passed successfully.

I log to PAMSrv as Domain Admin.

this cmdlet works fine

$ca = get-credential
New-PAMTrust -SourceForest "contoso.local" -Credentials $ca

This one however does not work

$ca = get-credential
New-PAMDomainConfiguration -SourceDomain "contoso" -Credentials $ca

I am using the same credentials for both...why would it work for one cmdlet and not the other? Are the steps in the guide incorrect?