GPRS shield with Free mobile sim card

Hello all, I recently purchased the sim 900 gsm shield ( I used it with the new Free mobile 2€ sim card. The NET LED turns on, then flashes every 0.8 seconds, then just turns off. When I press the PWRKEY, the same routine happens, an infinite loop. I checked the sim card with a phone, turned off the pin code. I tested the sim card, it works well on a normal phone. Though, when i inserted it in a old motorola, it required additional settings, sent by ams or something. Did I miss out something? Please help.

take a look at this post (in french)
It seems that you must change some code lines.
I don’t know more about it.

This solved my problem