problem with SIM900 GSM/GPRS

please I am currently working on a project in which I intend to use the SIM900 gsm / gprs (shield)

I have a problem When I feed my Arduino and I put my Gsm on it and I press the button (push-button, gsm)
status (LED) lights and NITLIGHT flashes , just for a second or two and then stop.
I don’t know what should I do!!?
Please I need help

WIN_20160414_230439 (2).JPG

So, no code running in the Arduino...?
Upload the simple Blink sketch, then try again - Just to see if the pair stay 'on' together

Possibly the power supply is not strong enough (A) to support the modem as well as the Arduino..