OSB : this service is not testable since all its operations require java arguments

I have created a simple Business Service to post a JMS message to a JMS queue.
When I test it from the Test Console being logged in with a user belonging to Administrators group, all is fine.
When I try with a user belonging to Operators, IntegrationOperators, Monitors, IntegrationMonitors it gives me a disable "debug" button and a funny message "this service is not testable since all its operations require java arguments".
Adding "IntegrationDeployers" group, logging out and in again seems to solve the issue.