gprs shield problem


i’ve received gprs shiled v1.2 and have problem with it.
seems like ‘serial port error’ or something.

  1. (Just strange). After power on, i see:

and nothing else. no RDY, +CFUN: 1, +CPIN: READY or something.

  1. Sim900 answer on AT commands, but:
    2.1. On default speed (19200, AT+IPR=0) it sometimes return strange answers, looking like serial port error.
    Instead of “OK” it return “ZOK” or “SOK” or “SK” for example.
    Instead of long answer (like reply to AT+CMUX=?) it return garbage in the middle of the reply string (garbage usually goes in 1 or 2 chars in the string, all other chars is fine)
    2.2. When i try to fix speed (AT+IPR=115200) i did not receive any good answer from module, only garbage.
    2.3. After back to default speed (AT+IPR=0) now i have each 4 chars per 7 chars lost. For example, i send

and got reply


So, shield lost each 4 bytes (sometimes 5 bytes).

Right now config is default (AT+IPR=0), arduino sketch from seeed wiki, speed default (19200), shield is untouched (in hardware part).

What should i do? Defect hardware? Send back?

forget to say - i try to use 2 different versions of arduino boards and problem is definetly not in them…