Live Midi Recording From Plugin

Hi,
I am new to Ardour(and DAWs in general) but have some self taught experience using a Roland Juno G hardware synth.
I have installed Ardour 4.7 on a PC running Ubuntu 14.04 and it seems to function OK connecting via Jack.
I want to run a plugin that looks like a synth (ie with a soft keyboard on the PC) and be able to record a sample in real time.
I have found a free plugin called Dexed which seems to be the kind of thing i want (it’s a replica Yamaha synth) and I can add this via the mixer and play the keys back via Ardour as a plugin. The problem is that when i try to record the live key strokes nothing seems to be recorded (not even a blank region is created). The only way that i can record seems to be via step recording which i find very awkward to do.
I can see the audio entering ‘master’ when i press the keys.
If i play about with the input/output MIDI function i can also sometimes see the audio entering the MIDI track for the plugin but still nothing records.
Please can anybody help me to understand if what i am doing is actually possible and if so where i might be going wrong?

Many thanks in advance
Damian

You may be best to join us on IRC (See the “Support” tab above for details), at least if the Central European to Central US time zones work for you. Figuring what’s wrong in a case like this is normally done by asking you lots of questions and getting you to try stuff. The problem is usually very simple and easy to fix once we know what it is. Web forums are excrutiating as a way to provide this kind of help.

Are you using the vertical keyboard on the side of the track in Ardour’s main window? You can’t record with that, as far as I know. You can either use some app like jack-keyboard to record MIDI, or buy some cheap external MIDI keyboard.