[R] persp plot help

[mike Ad.]

Dear list,

I am trying to make a perspective plot with persp(x, y, z). The problem is 
that z data set is incomplete, with lots of NA. And I can not get a smooth 
surface plot.
Could any one tell me how to generate a smooth surface with incomplete 
dataset?
(I tried to fill in some values for the miss values, but I still can not get 
a smooth surface in the persp plot)

/Mike