CWZTS0021E The 0 invocation is not valid.
Explanation
The invocation does not have an operation to invoke.
User response
Double-click the error message to open the invocation in the test suite editor. Select either a module, component, or interface. The operation for this invocation will populate the Operation field. If there is no module to choose, in the Configurations tab, add a module and then, in the Test Cases tab, select either a module, component, or interface to populate the Operation field.