Linking classes on a Sequence diagram using Rational Software Architect

Question

I am using Rational Software Architect to have a play at class diagrams and sequence diagrams. I created a class diagram with a number of classes. I then created a sequence diagram and tried create an operation/message between the classes.

I find that in some cases i cant create a link (message/operation) between some classes. I dont know why this is the case.

Are there some rules i should be aware of before i am able to link the classes on the sequence diagram?

Usually what happens is i click on the calling class, drag the mouse to the "Service" class to denote a method call. The problem though is that mouse shows a 'disabled' icon (similar to the no parking sign) so i cant link the two classes.

Answer 1

If you are using "combined fragments" in sequence diagrams it is necessary that the classes that are involved in the message (method call) are part of the same "fragment". If this is the case you can include new classes to one combined fragment by right-clicking on it and selecting "Covered Lifelines" -> "Add Covered Lifeline" on the context menu.