Problem in regression kriggin

Dear Ashton, Andy and the group,

Thank you very much for your suggestions. Yes, specifying ?data=data? is 
throwing the error and 

prk.rich<-krige(Richness~Elev, data, newdata=grd, model=fit.sph1)

is not giving that. But regarding your second suggestion to have elevation 
covariate at all location on the prediction grid or DEM, I am lost again. 
Please help me out. The issue is as follows:

Since I have no DEM at this moment, I have interpolated (ordinary krigging) 
the elevation of the whole study area based on 125 plots:

g.sph <- gstat(gelev, id="Elev", model=fit.sph)

p.sph <- predict(g.sph, model=fit.sph, newdata=grd)
a<-(p.sph["Elev.pred"])
library(raster)
raster(a)

s <- as(a, 'SpatialGridDataFrame')

str(s)

Formal class 'SpatialGridDataFrame' [package "sp"] with 4 slots
  ..@ data       :'data.frame':	20212 obs. of  1 variable:
  .. ..$ Elev.pred: num [1:20212] 70.3 70.2 70.2 70.2 70.2 ...
  ..@ grid       :Formal class 'GridTopology' [package "sp"] with 3 slots
  .. .. ..@ cellcentre.offset: Named num [1:2] 341960 2667253
  .. .. .. ..- attr(*, "names")= chr [1:2] "x" "y"
  .. .. ..@ cellsize         : Named num [1:2] 10 10
  .. .. .. ..- attr(*, "names")= chr [1:2] "x" "y"
  .. .. ..@ cells.dim        : Named int [1:2] 124 163
  .. .. .. ..- attr(*, "names")= chr [1:2] "x" "y"
  ..@ bbox       : num [1:2, 1:2] 341955 2667248 343195 2668878
  .. ..- attr(*, "dimnames")=List of 2
  .. .. ..$ : chr [1:2] "x" "y"
  .. .. ..$ : chr [1:2] "min" "max"
  ..@ proj4string:Formal class 'CRS' [package "sp"] with 1 slots
  .. .. ..@ projargs: chr NA

And then I tried regression krigging as follows:

prk.rich<-krige(Richness~Elev, data, newdata=s, model=fit.sph1)

But it gave me following error:

Error in gstat.formula.predict(d$formula, newdata, na.action = na.action,  : 
  NROW(locs) != NROW(X): this should not occur
In addition: Warning messages:
1: 'newdata' had 20212 rows but variable(s) found have 125 rows 
2: 'newdata' had 20212 rows but variable(s) found have 125 rows

I have gone through http://spatial-analyst.net/wiki/index.php?
title=Regression-kriging_guide  and other possible different guidelines but 
could not come to any conclusion.

Any help is appreciated.


Best regards,

---------------
Md. Abdul Halim
Assistant Professor
Department of Forestry and Environmental Science
Shahjalal University of Science and Technology,Sylhet-3114,
Bangladesh.
Cell: +8801714078386.
alt. e-mail: xou03 at yahoo.com