With the 530 you need to essentially press the lock button twice on the same target: once to get a TWS lock then a second time to get an STT lock once you are ready (i.e happy that there are no higher threat targets on your VTB that you might want to address first). If you fire a 530 in TWS it will not track your target. Also, if you activate RDO mode after you have selected a 530, it will automatically TWS lock the highest priority target. It is then up to you to STT lock that target before firing.