execl difficulty

[python newbie]

Can anyone tell me why this would cause "Invalid Number of Parameters" while
trying to compile (or interpret or whatever)

import os
os.execl("C:/WINDOWS/system32/xcopy.exe","E:/MainWeb/dreampics/*.*","E:/Main
Web/dp")

Here's what the Python reference says:
     execl(path,arg0, arg1, ...)

if you can see something obvious, please tell me
thanks
Steve