Problems with sensor and RTC and Arduino nano

Dear all,

i'm totally a beginner here (and in Arduino), so I hope I won't break any rules.
I've got an arduino nano and a Arduino Nano IO Shield SKU DFR0012.
I've managed to connect a pH sensor and a SD card, and to record the data.
Now, i'd like to add some sensors (let's begin with the Gravity I2C VEML7700 Ambient Light Sensor SKU SEN0228) and a RTC (the Gravity I2C DS1307 RTC Module SKU DFR0151) to record the time at the same time of the measurements.
First I had a lot of problems with the libraries, but now I think I understand more or less how it works, so I can compile the program examples and download them to the nano.
But it seems that my connections are not good as it does not recover any data (just 0.00 lux for the light sensor and no connection for the RTC).
I have connected both sensors to the IC/TW ports of the shield (5V/GND/SCL/SDA) which seems the way to do it, right?
Did I do something wrong?
I've tried to make a picture of the set-up, hope it will help (edit : sorry it does not seem to work)


Thanks a lot,
Cheers