Bluetooth HC-05 module Response error

Hullo all , I 'm using the HC-05 Bluetooth module for the first time ..... i wanted to get into AT Command mode , so i wrote my own UART library and it seems to be working fine (Tested with another mega device and it sends and receives properly throught interrupts) , the problem is that after each command , say "AT\r\n" test command , i get only the first character of the response , n the rest is messed up , for example , i get "OI" or "Oi" after the test command instead of "OK" ...... any ideas ? (NOTE: im not using arduino board , just ATmega16 device).