[R] Could not find function "pointsToRaster"

[Ogbos Okike]

Dear All,
I have a script that draws longitude and latitude of lightning
occurrence. This script was running fine before. But when I changed my
system and do a fresh install on another laptop, this error persist.
 source("script")
Error in eval(expr, envir, enclos) :
  could not find function "pointsToRaster"

I have tried to see if  there is any other package I need to install
to take of the problem, I could not see. Already, when I installed
raster, it installed its dependencies such as sp.
Can any body please bail me out.

Thanks
Ogbos