tsl2591 Wire.endTransmission A4 doesn't work


My problem is pretty basic I hope.

  1. Have an arduino uno and a TSL2591 sensor.

  2. Did the wiring described here: Wiring & Test | Adafruit TSL2591 High Dynamic Range Digital Light Sensor | Adafruit Learning System

  3. Run the code and the single message is "Starting Adafruit TSL2591 Test!"

  4. Use I2C scanner code from http://playground.arduino.cc/Main/I2cScanner

  5. There is a problem with the line error = Wire.endTransmission(); - the execution doesn't pass further

  6. Step 5 issue is related to the wire between SDA (TSL2591) and A4 (arduino uno) - if I don't connect them, then Wire.endTransmission() works, even if the I2C scanner is finishing without finding any sensor

Question: what exactly is wrong? The TSL2591 sensor is damaged or what?