Seeeduino Base Shield i2c Problems


I am relatively new to Arduino so I apologize if this is a simple problem.

I have been experimenting with an Arduino Yun + Seeeduino kit for AWS IoT. The IoT part is not really important for this question. The kit includes a Grove LCD module, which works just fine if I plug it into the i2c port on the Yun itself. However, if I plug in the base shield (v2.0) and then plug the LCD into one of the four i2c ports on the base shield the LCD will not work.

I also found that if I have the LCD plugged into the YUN and then add the Grove base shield, the LCD stops working.

I've been running the i2c_scanner example code and it works just fine as long as the base shield is not used.

Is there something I must do to get the base shield i2c ports to work? I tried changing the setting of the voltage switch to 5v, but no change.

Looks like I found the answer to my own question. There is a conflict between the i2c ports and D2 & D3 on the Grove base shield. I had a button and an led plugged into those ports and that was messing things up.