The error message about no search methods means that you haven't provided a value for the parameter in your conection definition. You always need to provide a value, otherwise the wrapper won't be able to connect to your web service.
If you don't want to always provide a value, you can define a default value in the following way:
1. Create a derived view and define a view parameter with a default value
2. Define a WHERE condition in the derived view that assigns the value of your view parameter to the parameter in your connection definition
You can read about how to do this in more detail in the "Parameters of Derived Views" section of the Virtual DataPort Administration Guide.
Hope this helps!