could the recipe analyzer be wrong?

I just entered in all the ingredients for Applesauce Bran muffins from the back of a box of Quaker unprocessed bran, because I wanted to see how many fewer calories there would be if I substituted Splenda for the sugar in equal amounts (1/2 cup). Interestingly enough, with no other changes, the recipe using sugar was 147 calories per muffin, and with Splenda it was 153 calories. I don't understand that, as Splenda is supposedly a zero calorie sweetener.

Here I was expecting to shave off calories by using an aftificial sweetener and instead it's adding them. Can you think of any reason this would happen? This will definitely have an impact on how (or if) I use the analyzer for other recipes.

Thanks.

It could happen if you entered the ingredients or units of measure wrong.  If you'll foward me a link to the actual recipe you entered, I'd be glad to have a look at it and give you tips to correct it.  The analyzer is only as good as the data it correlates - it's only a computer program. 

Thank you. I just send you the links in an email.

Per gram, Splenda has about 1carb, giving it roughly 4calories/gram