Ha! See how beautiful I wrote this script? So much work but pay it!
Hm ... Tell him or not?
What do not you say?
Ehhh ... For the boss ... I did today format by accident, backup all the boot's, and removed the contents of SP3 .... This is all because of this stupid secretary ...
I had difficulty understanding the dialogue in most of these. If English isn't your native language, consider writing in your native language.
Even when I did understand, I often didn't find them humorous. Remember, just because something would be funny if it happened in real life doesn't mean that it will be funny in a comic. Look at other comics (or comedians, movies, whatever) that you find funny, and think about what makes them work. Pay attention to the elements of a joke -- the set-up and the punchline. Your last comic is funny because something is happening that isn't what we'd expect. Try to work with that: use the first two panels to make us expect something, then, in the last panel, deliver a punchline that shatters that expectation. Here's a great example:
Thanks for the words of understanding. I come from Poland and I do not know how to build some opinion. What you say certainly motivate me. :) PS. Great comic :D