GRASS 7.1 (dev.) i.landsat.toar error

I am working with Landsat 8 image acquired in 2014. I am trying to convert the raw image (DN) to Top Of Atmosphere Reflectance/Radiance (i.landsat.toar) in Grass 7.1 (still under development). The reason for using this version is that it is caters for landsat 8. I specify the metadata file and load the information etc. I get the same error every time:

ERROR: Unable to open header file for raster map

I would appreciate any suggestions.

Base Name of input raster band: LC81700832014160LGN00_B1@PERMANENT Prefix for output raster maps: LC81700832014160LGN00_B1.toar Name of metadata file: C:\Users\carinswart\Documents\GIS_DataBase\Landsat8\GHT\09June14\LC81700832014160LGN00_MTL.txt

I have tried to be careful not to leave gaps in my file names...