First of all, congratulations are in order! #1 - You finished a script. #2 - You risked submitting it to a 'cold read.' Wow, that's fabulous. For those of you unfamiliar with the term, a 'cold read' is a gathering where a group of actors meet, are handed a script and within about 30 minutes are acting it out. Often it's just the opening act of a feature length screenplay that's read. And it's one of the scariest and most exhilarating rides on the planet. Hearing your words come out of an actor's mouth is one of the BEST WAYS to gauge the effectiveness of your dialogue and pacing of your writing.
And as you found out, a cold reading can also reveal some of the weaknesses of your script that might have slipped by some of your other critiques. From the comments you received it sounds as if you might have been shanghaied by the LEFT side of your brain while you were writing. As many of you know, who follow this screenwriting blog, I believe any really good story (but especially screenplays) are a balancing act between RIGHT brain creativity and LEFT brain structure.
Really well plotted thrillers and heist movies delight us with the mastery of the turns and twists of their plot (left brain). But if they contain heart-wrenching scenes of loss and betrayal - those deeply rooted emotions come from the right brain. Right brain function is all about universality. Check out Jill Bolte Taylor's fabulous and passionate TED talk http://www.ted.com/index/php/talks/jill_bolte_taylor_s_powerful_stroke_of_insight.html
which gives a beautiful & passionate explanation of the relationship between the TWO brain hemispheres and the impact on us as individuals.
What's probably missing in your script is that moment (s) where the camera focuses on the hero/heroine and we get to SEE their pain/reaction/ emotional response to whatever is happening to them. We need emotional connection to the main character to actually care enough to plow through the next two hours of their life with them. EARLY on in your script give us an emotional LINK to your heroine/hero and then reinforce the connection periodically throughout the film. Those EMOTIONAL ties will keep us cheering your character through to the bitter or sweet finale of the film.
I hope this helps. And I do wish you luck with your screenplay. Let me know when you've completed the rewrite.... I'd love to read your work!