Formula fields DO NOT WORK!

Formula fields DO NOT WORK!

I'm in my free evaluation stage and I'm experiencing some serious glitches.

I needed to calculated expected revenue in another way (even though I know I can't do forecasting on it).  So first, I created a custom % field called "Confidence to Build".   Then, I created a new custom formula field "TBG Expected Revenue" which I arrive at using the formula:

TBG Expected Revenue = ${Potentials.Expected Revenue}*${Potentials.Confidence to Build (%)} 

So, let's say a $1M Potential with a confidence of 50% is normally $500k expected revenue.  If the confidence to Build were 50% as well, the TBG expected revenue would be $250k.

I'e experienced two problems: 

1) In theory, whenever I change the stage of a potential, the TBG expected revenue should be calibrated accordingly.  But that's not happening.  My TBG Expected Revenue value is remaining static when I change the stage.
2) If I attempt to change the Confidence to Build value, the calculation seems to ignore the fact that it is a percent field and instead multiplies it by the integer I enter.

HELP PLEASE!!!