Decker and Dialogizer should always work with each other, unless there's of a very old copy of one of them and a very new copy of the other. So let's check that. The current version of Dialogizer is 1.7 and the current version of Decker is 1.63, for reference.
You can see the current version of your module (and update to a newer one if needed) in the same popup where you transferred it into your project from the Dialogizer example deck [File > Resources].

You can see the current version of Decker by using the menu [Decker > About].
If the version numbers seem fine then the other thing to check is whether you have dd.open[deck] before you dd.say[] anything. Like this:
on click do dd.open[deck] dd.say["hi"] dd.close[] end
Hopefully one of these two things will be the answer, but if not please let me know.