8051 timeout error

Does anyone know why every time I try to re-flash my 8051, I keep getting error: "timed out" . I have to keep pushing reset and retry until it goes through. Any known issues with it? I'm using AT89C51RD2.
Thanks,

which programmer you are using ?

he is programming via ISP.. i think..
shawn please check carefully if your controller is in programming mode.. during reset PSEN should be low and ALE not connected..