yeah... Me too never seen 18 pin LCD...
kiyani014, can you post pinout diagram of 18 pin LCD so that we can help you...
For 16 pin LCD, connect RS, RW, EN and Data bus to microcontroller
Here is the pinout
Pin No. Label Description
1 VSS Ground
2 VDD Supply Voltage
3 VO Contrast adjustment voltage
4 RS Register select signal
5 R/W Read / write select signal
6 E Operation (read/write) enable
7 DB0 Low byte data bit
8 DB1 Low byte data bit
9 DB2 Low byte data bit
10 DB3 Low byte data bit
11 DB4 High byte data bit
12 DB5 High byte data bit
13 DB6 High byte data bit
14 DB7 High byte data bit
15 A Positive LED backlight (Anode)*
16 K Negative LED backlight (Cathode)*