Hi Everyone - I'm new to the Boards, so please bare with me if any of this is "out of whack"

Am trying to insert a basic Age Formula onto a Leads Report, however any way I do it, I get a sytax error of 

"Error: Invalid custom summary formula definition: Field Status does not exist. Check spelling."

IF(ISPICKVAL({!Status} , "Open"), ROUND(NOW()-{!CreatedDate}, 0), NULL)

Even with this formula, I get:

ROUND( NOW() - {!CreatedDate}, 0)

"Error: Invalid custom summary formula definition: Field CreatedDate does not exist. Check spelling."

I'm actually just copying/using formulas posted by others as the function is basic and exactly what I want/need.  Again, apologies if some/all of it doesn't make sense, I'm new here - and not systems admin by any right other than, "You're in Charge of SFDC" by my upper managment.

Please help