Well no offense but for one thing you are still not showing the error from the script editor and for another ...

" ERROR: Select a subdivision surface which you want to tessellate."

Is an error from trying to convert a subdivision surface to a polygon surface where you have not selected a subd surface to convert. Is the screen shot above of a subd surface? If not then it's pretty clear why you are getting the error above. It looks pretty much like a polygon surface to me.

So we still are left to guess at your original problem of trying to convert a polygon to a subd.

Please try to convert from polygon to subd as you did in the original post and when / if it fails please open the script editor (the little icon in the bottom right hand side of your interface) and copy and paste the actual detailed error from that screen.

Based on your screen shot it would seem that the default base mesh size of 1000 should be large enough but without seeing the full error description from the script editor when you try to convert from polygon to subd we are all just guessing!

Seriously, I am not trying to be rude but without seeing the detailed message you may as well just make a post and say "Something is broke! Please help." You'll have about the same amount of luck getting a solution.

Thanks