we'll eventually be able to nail down your problem ... but ... it would be a LOT quicker if you can post your .RSS file ...
my "best guess" so far: you don't have the analog input signal properly scaled BEFORE it is presented to the PID's PV (process Variable) location ... for the PID instruction (in an SLC system) to give optimum results, the PV location MUST range in value from 0 to 16383 ...
possible cause for confusion: when some (many?) people hear the word "scaled" they immediately think of values expressed in "engineering units" such as "gallons per minute" or "degrees F" ... this gets confusing when you're reading some of the Allen-Bradley manuals, because they mention that the input signal must be properly "scaled" before it reaches the PID ... (note that I used the word "scaled" in exactly the same way in the last paragraph) ... so to some people, the book instructions mean "convert the input signal into engineering units before it reaches the PID" ...
that's WRONG ... in simplest terms, the range "0 to 16383" is SCALED - and SCALED properly for the PID's PV input ... if this "scaled" terminology is what's confusing you, you are NOT the first to fall into the trap ...
if this doesn't help, try posting your .RSS file ...
PS EDIT ... it looks like my distinguished colleague Mark Buskell has come up with the same "best guess" while I was typing ...