I don't know what your problem is but try this- put a little air in the tube before installing, just enough to make the tube round. I find that using my mouth to blow into the tube will give me the right amount of air. This will help avoid pinching the tube between the rim and the tire bead. If there is any part of the tube caught between any part of the rim and the tire bead it will lift the tire off of the rim. I quit using Vredestein tires because I thought the beads are too small and too easy to unseat.
If your rims are 25 mm across the inside they are too wide for 23 mm tires IMO.