Hytera MD788G with DMK URI

I am trying to make a connection with Hytera radio md788g using db-25 connector using URI and windows IAXRPT app. I am facing some configuration issues maybe, I configured my simpleusb.conf:



hdwtype=0 ; Leave this set to 0 for USB sound fobs modified using
; the instructions from usbfob.pdf. Use a setting of
; 1 is for Dingotel/Sph interfaces.

rxboost=1 ; 0 = 20db attenuator inserted, 1= 20db attenuator removed
; Set to 1 for additonal gain if using a low-level receiver output

carrierfrom=usb ; no,usb,usbinvert
; no - no carrier detection at all
; usb - from the COR line on the modified USB sound fob
; usbinvert - from the inverted COR line on the modified USB sound fob

ctcssfrom=no ; no,usb,usbinvert
; no - CTCSS decoding, system will be carrier squelch
; usb - CTCSS decoding using input from USB FOB
; usbinvert - from the inverted CTCSS line on the modified USB sound fob

txmixa=voice ; Left channel output: no,voice,tone,composite,auxvoice
; no - Do not output anything
; voice - output voice only

txmixb=no ; Right channel output: no,voice,tone,composite, auxvoice
; See txmixa above.

invertptt=0 ; Invert PTT 0 = ground to transmit, 1 = open to transmit
; This is the collector lead of the 2n4401 on the modified
; usb sound fob.
; please refer to the howto for the procedure to do this.

duplex=1 ; Full Duplex

I can transmit voice from radio to iaxrpt but cant send from iaxrpt to radio
what could be the reason. I am new to this all and need help. Helping in pins connection will be appreciated too. Thanks