Date of next increment after joining from higher to lower grade pay

Respected experts, i was working as radiotherapy technologist with tata memorial hospital, Mumbai from 06/2006 to 23/02/2015 in the scale 9300-34300 with pay of 13490 and grade pay of 4600. I had applied to JIPMER, Puducherry, through proper channel and joined JIPMER on 27th Feb. 2015 for post of X-ray technician (Radiotherapy) in the scale 9300-34000,grade pay 4200. At the time of relieving from TMH (on 23 the feb 2015) my basic salary was 13490+4600(grade pay). JIPMER has fixed my salary as 13490+4200 with effect from 24 the Feb 2015. However no increment was given to me on 1st July 2015 on the grounds that I had joined on lower grade pay (4200) and i had not completed 6 months on that grade pay. Please let me know if I am eligible for increment on 1/07/2015 and under what rules. Also there is loss of D.A with above fixation. I think along with my pay,the D.A both has to be protected too.Also advice on the how pay will be fixed. Thank You.