Problem connecting/ Sim808 init error: Arduino Uno and Sim808 v.2.2.9 GPS GSM

Hi everybody, I’m still a student and newbie using this module. I have arduino uno R3 and a Sim808 v2.2.9. I have search many pages and forums but I can’t fix it, I need a help. When I upload a code using Arduino IDE then when I click the Serial Monitor to see the output it always says “Sim808 init error” again and again. And I tried another code different code but same logic and it always says “gps initializing” hope someone can help me. As you can see in the picture the NETSTAPPS the NET is blinking slowly and the STA is always on but the PPS is off I don’t know why I just implemented the code and it always said that the sim808 didn’t initialized.