Seeed Base Shield does not work with 1602 display

I have been unable to get the 1602 display to work with the base shield. I finally removed it from my UNO board, and connected it using jumper wires and it works perfectly. I’m new at this and trying to understand how software (Sketches) interface with the hardware.The display works when the SDA is connected to A4 and SCL is connected to A5 on the UNO. How does one get the A4 and A5 to connect to the SDA and SCL signals?

Hello, which base shield is being used?

Grove Base Shield V2.0 for Arduino

I have used it, you just need to upload the LCD display code and connect the LCD to one of the IIC ports on the base shield using a Grove cable to use it.

Where do I get the LCD code?

#include <Wire.h>
#include "rgb_lcd.h"
rgb_lcd lcd;
const int colorR = 255;
const int colorG = 0;
const int colorB = 0;
void setup() 
    // set up the LCD's number of columns and rows:
    lcd.begin(16, 2);
    lcd.setRGB(colorR, colorG, colorB);
    // Print a message to the LCD.
    lcd.print("hello, world!");
void loop() 
    // set the cursor to column 0, line 1
    // (note: line 1 is the second row, since counting begins with 0):
    lcd.setCursor(0, 1);
    // print the number of seconds since reset: