Need help figuring out problem

I am doing a menu system based on SoftWarewolfes smooth ios scroll example (I have cleaned out all ios extensions however so this example will work on all platforms). However I wanted it to be a bit more flexible in regards of changing and adding objects without having to "hardcode" everything after a change. So I am trying to do it in away that adjust automatically to a value I call "ObjectGap" , by just typing in the x distance between the objects the menu are supposed to center on the rest should be automatic. It works quite fine, but I got stuck with something being off. I have 4 objects in the example, and when you click and hold to drag the menu back and forth it behaves correctly between the first 3 objects (it snapps to the closest when releasing the mouse). But the last object there is something fishy. I tried to demonstrate in this video, look where the center of the screen is and the red number:

https://dl.dropboxusercontent.com/u/...-14_201324.wmv (If online browser is having problem, then right click link and pick "save link as")

I have attached an example mfa, I am 95% sure it is event line 27 that needs to be modified. I assume it is a problem with multiplying the value with 1.5 that is the culprit, but I cant figure it out how to adjust to make it always work..