ov7690 SCCB interface

hi:
    i am trying to interface 0V7690 with SAM kit.  ov7690 has SCCB
interface. which i came to know that can be run over TWI interface.

 I have perfectly running code for TWI. and can read and write I2C based
EEPROM.

but when i trying to READ ID (from register 0x0A)from ov7690 which has
slave adress of 0x43 to read i got error of time out, in other words it
didnt respond!!

 my controller is running on 3.3v. and ov7690 is on 2.8v 
 i have  bi-directional MAX3002 level shifter between them. and also
pull-up with 10K resistor on both sides. 
 I didnt connect HREF,VSYNC,PCK and data lines, coz want to test SCCB
interface first. MCK of 24MHz is given by controler to OV7690.

any one know plz help!!

	   
					
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