When I try to merge rasters I got following error message:
_gdal_array = swig_import_helper() File "C:\PROGRA~1\QGISDU~1\apps\Python27\lib\site-packages\osgeo\gdal_array.py", line 18, in swig_import_helper import _gdal_array ImportError: No module named _gdal_array
I tried to update Qgis to 2.2 and did a the whole OS4GEOW installation, as recommended in an other thread.