I've been using JMeter and Gatling to record a scenario on a JSF2 PrimeFaces 4 web app, in order to load test it. The recording goes well with both tools, but the replay of the scenario fails because a click action on a commandButton opening a popup dialog doesn't fire the associated event. Said commandButton gets enabled by the previous action in the scenario (a dropDown selection in the same table row). 

That issue happens only when running the scenario on the performance testing tools, not when navigating in the browser UI.

I've compared the arguments of the POST requests picked up by Firebug and Gatling/JMeter, and they seem completely identical (management of the JSF ViewState is correctly set up btw). I've also increased the pauses between actions during the scenario, but to no avail.

Any ideas on what the recorders and/or I could be missing?
Thanks in advance.