I would try something like:
+ Hold mouse button down
+ Mouse is over object
-->Set private variable "is dragging" to 1
+Private variable "is dragging" equals 1
--->Set object.X to Mouse.X
--->Set object.y to Mouse.Y
+Hold mouse button down (negated so it's a NOT)
--->object set private variable "is dragging" 0
That should work.
~Sol