Did you program the new Jackson Tower frequencies into your scanner? They should look like this:
851.48750
851.68750
852.56250
852.73750
852.96250 Alternate Control Channel
853.06250 Control Channel
Another issue might be if the Jackson Tower is in site trunking mode for any reason. If so, it would not network with the other nearby towers, but may have some local traffic in the Jackson area, but nothing for other areas.
73's
Ron