In order to get more information on the issue, post the output of the following commands
a) Create connection to Raspberry Pi (for the first time)
>> mypi = raspi
b) List all the available I2C bus available and their speed
c) Scan all the I2C buses available to get its address. '<name>' is obtained from the output of mypi.AvailableI2CBuses.
d) Create a connection to all the addresses obtained in the above step for every I2C bus.
>> i2cdac = i2cdev(mypi,'<name>','<address>')
e) Write value to every I2C bus connected in above step
Refer to the link below for more information on the commands: