TCA9548A I2c scanner can't find any devices

i have two max14574 driver(with the same fixed address), so to comunicate with them i'm trying to use a tca9548a MUX breakout. i'm following the adafruit tutorial(at:, but when i launch the tca9548a i2c scanner, it can't find any devices connected on the port. launching the i2c_scanner at(Arduino Playground - I2cScanner),with only the tca9548a connected, it gives me multiple error at random address if tca9548a is connected to 3.3V, instead if connected to 5v the result is no device found. if tca9548a is connected and other devices are connected i2c_scanner find only other devices adress. i don't understand which is the problem the problem. can someone help me? thanks in advace.

do you have 4k7 pullups on the SDA and SCK lines?

Thank for your reply.
no, but in every tutorial i see no one use it. do you think i could try?

I have the same problem. I am using the Adafruit Tca9548a with no pullups like in the tutorial. i tried it also with 5k on SDX. Any suggestions?