Have you checked the LCD's datasheet to verify the pin assignments? Look at section 5 on page 3.
Are they numbered with plain numbers or are they marked by function? According to that, the LCD pins d4, d5, d6 and d7 are LCD pins 11, 12, 13 and 14.
The datasheet I found, which is 10 years old, says that pin 15 and 16 (backlight) are not used.