SMS ERROR

I would like to send a message from my shield to my mobile. i had tried 2 examples code from 2 different libraries. Currently i’m using Arduino Uno Rev3 and Icomsat v1.1 sim900. i had compile the coding and i din’t get any error for the coding, but i DID NOT received any sms from gsm. Anyone know why i could not received message?
The steps i did:

  1. stack icomsat v1.1 onto Arduino Uno Rev3. Connect antenna, USB and 12V/1.2A power adapter. Insert SIM card(Empty message inbox, $5 inside)
  2. switch the button on gsm shield to UART_Port, TxD on pin2, RxD on pin3.
  3. PWR light is red, Status light is yellow and Net light is blinking yellow.
  4. Change the country code and phone number in the coding. Upload and compile the coding with Arduino 1.0.3.
  5. Done compiling without coding error.

libraries 1: https://code.google.com/p/gsm-shield-arduino/
Result from SerialMonitor:

GSM Shield testing.
status=READY
SMS sent OK

libraries 2: GitHub - jgarland79/GSM_Shield: GSM Library for the SIM900 chip and the GBoard Arduino GSM development board
Result from SerialMonitor:

system startup
no call
Command: s
Check_Protocol
Send SMS to +60168908871
SMS ERROR