SHIELD-LCD16x2 I2C working, LCD not displaying.

[m_k_johnson]

Hello,
I hook up the SHIELD-LCD16x2 to an Arduino. 
Running example Buttons_And_LCD:

- lcd.readButtons() works = so I2C is working. 
- lcd.lcdWrite() does not show anything on LCD.

Note: the LCD display is not lit.  Should it be?  The SHIELD-LCD16x2 is plugged into 3.3V/GND of Arduino.

Any thoughts on debugging is much appreciated.
Thank you.

[Stanimir5F]

You said that 3.3V and GND are plugged. How about the 5V line?

Because as you described it it looks like the 5V isn't. I can't guarantee you that exactly this is the problem you have encountered, but if 5V aren't presented the LCD won't work for sure.

Stanimir, Olimex