[GRASS-user] what is requried when import data to grass?

[maven apache]

When import some raster data to grass,I use the following cmd:1) g.region -d
2) r.in.gdal input=D:/test.TIF output=testTT --overwrite
I got the error message as following:
---------------
Projection of dataset does not appear to match current location.


Location PROJ_INFO is:

name: UTM

datum: nad27

nadgrids: conus

proj: utm

ellps: clark66

a: 6378206.4000000004

es: 0.0067686580

f: 294.9786982000

zone: 13


Import dataset PROJ_INFO is:

cellhd.proj = 0 (unreferenced/unknown)
------------------------
3) change the cmd to " r.in.gdal -o input=D:/test.TIF output=testTT
--overwrite "  I know this override the projection,however I am not sure the
potential  effect to the data.

Now the tiff is imported,and I got testTT.bule testTT.red testTT.green, then
I  open them can only see blank. So I wonder it is caused by the projection
or location,I use the spanish data as the default location , and I tried to
create new location and mapset but never success...
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