I can't tell you how many scripts I've critiqued from writers who were absolutely certain their script with in top form and ready to be sent to agents, producers, script comps, etc. They'd send it to me, saying, "Just clean it up a little; fix the formatting, correct the spelling problems." Then I start reading the script and it's dreadful from the first pages. Not only are there the aforementioned formatting and spelling problems, but also insipid dialogue, superfluous/overly long descriptive passages...and one of the biggest problems: a 37-page idea stuffed into a 120-page screenplay. Ugh.

As some have suggested here, get your work looked at by professional writers, or at least non-pro writers that can read your script with a critical eye and provide an intelligent evaluation. (I suggest you find 5 writers that can provide a critique. If one says a scene is fine and four say the scene needs work, it's a safe bet the scene needs work.)

So, in a nutshell: Your script isn't nearly as "ready to go" as you think it is. Critique, rewrite, rewrite, rewrite, critique, rewrite. You get the point.

Good luck!