SOAP Method with WSDL Support

I'm trying to use this component, and promote some of the parameters for the web service up to the parent.

However the expressions in the parameters list do not appear to really be expressions. They simply pass the text to the web service. So whatever expression I put as a parameter to the web service, just gets passed as straight text to the web service instead of getting evaluated first.

Do I have to hard code the values as strings?

Thanks.