Error in .local(.Object, ...) : 
  `DDtotal_cohort1.tif' does not exist in the file system,
and is not recognised as a supported dataset name.


Error in .rasterObjectFromFile(x, objecttype = "RasterBrick", ...) : 
  Cannot create a RasterLayer object from this file. (file does not exist)
Calls: brick -> brick -> .rasterObjectFromFile
Execution halted