Arduino Mega PS2, don't work after power on off

[vindhyachaltakniki]

1. I am using arduino mega 2560. A PS2 keyboard is connected to read keys & display on segment.

2. Issue faced is, when power in turned off & applied again on entire system(MCU+PS2 converter+usb keyboard), keyboard don't get initialized again automatically, that is I am not able to read any keys unless I remove the keyboard from socket & connect again, then I can read again.

3. There is small USb to PS2 converter used. Keyboard is usb.

4. what could be issue.

5. below is keyboard code:

const int DataPin = 19;
const int IRQpin = 18;
PS2Keyboard keyboard;

keyboard.begin(DataPin, IRQpin);  
keyboard.clear();
        c = keyboard.read();
        Serial.println(c);