Help My AI aircrafts will not land.(AFCAD-TT Tools)

Hi all, Using AFCAD I have added a tower at an airport that previously had none. I then programmed flight plans from and to this airport using TT Tools . The end result is that I now have atc control at this airport. I have traffic taking off from this airport. The problem is that incomming traffic seems unable to land. They arrive in the control area (apox. 10miles), get clearance to land, and make it to final. Then at about 0.5miles they declare a missed approach.They then complete the circuit(if VFR), if IFR they are vectored for a visual approach. They again make it to final, and the same thing happens. after the third attempt,the aircraft just dissapears.It appears that the traffic flies the approach too high. In an attempt to remidy this I have used AFCAD to extend the runway from the default 3002ft to 7002ft. still the same result.