proc gcontour

[jkanters]

I have a dataset with 4 variables

ptid         id

loghz      y

sequence x

logs        z

the value of z is spaced in the interval from 0 to 1;

I have made a dataset grided by g3grid, which works perfectly.

I want know to plot each id (ptid) with the same z contour levels (logs). However proc gcontour overrules my clevels. It is because for the specific id (ptid) the data does not contain values in some of the range. But I dont care. Then proc gcontour should simply plot with the clevels it has or in worst case plot no contours at all. How can I stop proc contour trying to be intelligent and let me decide the clevels. 

proc gcontour data=grided; by ptid;

   plot loghz*sequence=logs/

       levels= 0.2 0.4 0.6 0.8

    clevels=white red orange yellow green blue black

    vaxis=axis1

    haxis=axis2

    ; 

run;

quit;