Both OLED's not working

I bought both Monochrome 0.96" 128x64 OLED graphic display PID: 326 and Monochrome 128x32 I2C OLED graphic display PID: 931, I plug in power and I get nothing. I have verified 5v on 326 and 3.3v on 921.I have also loaded sample software and nothing. Any advice?

UPDATE; I was able to get the 128x32 I2C OLED to work.

Do I need to change other code to get the 128x64 SPI to work? I already changed the header to #define SSD1306_128_64

Find an I2C scanner sketch on the web and run that to see if the display is at the I2C address that you think it is.

If it is not at address 0x3C then you will need to either change the header file or, more conveniently, put it in the begin() function in your sketch.