Hi - I am running GrovePi+ along with a 3.5" LCD screen [http://www.waveshare.com/product/3.5inch-RPi-LCD-A.htm] [http://www.waveshare.com/wiki/3.5inch_RPi_LCD_(A)#FAQ]. The setup allows me to run the python script without needing a monitor or network to run the command. What i notice is that while the grove_sound_sensor.py runs fine when connected to HDMI or over SSH, when I run the command with the LCD screen having the display, the sensor only returns an Error. With the LCD i2cdetect works fine as well as the grove_led_blink.py samples work as expected.
I already upgraded the firmware to 1.2.5 but have the same issue.