Can not use atmega8 with external crystal

[rayle1360]

I am trying to use atmega8 with external crystal but with no luck. internal oscillator works fine and I can upload sketch without any problem. but when I burn bootloader with external 16mhz crystal, I get "avrdude error: programmer is not responding". the crystal is fine because when I use menu sketch>upload using programmer then it works. but I want to use it like a real Arduino to upload sketch via serial. any sugestions??