How to calculate distances in QGIS field calculator?

So I'm using qgis 2.6.0 and I have a csv (converted into a .shp) with two geometry columns, I want to create a new column with the distance between the two geometry:

shot.lat    shot.lon    haul.lat    haul.lon
57.563      -12.986     57.534      -12.985
57.7        -13.304     57.67       -13.299
57.611      -13.529     57.582      -13.538
57.594      -13.294     57.565      -13.315

57.432      -13.314     57.402      -13.304
57.339      -13.053     57.311      -13.072

I am trying to use the function geometry function "distance" with the following expression:

distance( geomFromWKT( 'POINT("shot.lon" "shot.lat")' ) , geomFromWKT('POINT( "haul.lon" "haul.lat")' ))

This should then create a new field with the distance between the points. When it runs though, it just returns Null. Am I missing something obvious?