How to show call action arguments in a sequence diagrams

Hi, in my sequence there is a call message from an object A to an object B. This message consists in an invocation of a method foo(). This method accepts a parameter (bar). I have specified the argument “bar” in the Arguments tab of Call action specification, but this argument is not shown in the sequence: the “caption” of the message is simply “foo()” instead of “foo(bar)”. How can I get my goal?

I found by myself the answer to my question: