For some reason the following unifier is not working anymore

Unifier u = new Unifier();
u.setColumnNames( "tile" ); //$NON-NLS-1$
u.addPattern( uri, ImagePyramidTileBeanUtil.PYRAMID_TILES, "tile" ); //$NON-NLS-1$ //$NON-NLS-2$
u.addPattern( "tile", ImagePyramidTileBeanUtil.PYRAMIDTILE_LEVEL, Resource.literal( level ) ); //$NON-NLS-1$
u.addPattern( "tile", ImagePyramidTileBeanUtil.PYRAMIDTILE_ROW, Resource.literal( row ) ); //$NON-NLS-1$
u.addPattern( "tile", ImagePyramidTileBeanUtil.PYRAMIDTILE_COL, Resource.literal( col ) ); //$NON-NLS-1$
TupeloStore.getInstance().getContext().perform( u );
for ( Tuple<Resource> r : u.getResult() )

{ return r.get( 0 ); }

throw new NotFoundException( "no tile found" );

it will return an empty set, however the following one (using the same level, row, col) will return results.

Resource rl = Resource.literal( level );
Resource rr = Resource.literal( row );
Resource rc = Resource.literal( col );
Unifier u = new Unifier();
u.setColumnNames( "tile", "level", "row", "col" ); //$NON-NLS-1$
u.addPattern( uri, ImagePyramidTileBeanUtil.PYRAMID_TILES, "tile" ); //$NON-NLS-1$
u.addPattern( "tile", ImagePyramidTileBeanUtil.PYRAMIDTILE_LEVEL, "level" ); //$NON-NLS-1$
u.addPattern( "tile", ImagePyramidTileBeanUtil.PYRAMIDTILE_ROW, "row" ); //$NON-NLS-1$
u.addPattern( "tile", ImagePyramidTileBeanUtil.PYRAMIDTILE_COL, "col" ); //$NON-NLS-1$
TupeloStore.getInstance().getContext().perform( u );
for ( Tuple<Resource> r : u.getResult() ) {
if (rl.equals( r.get(1)) && rr.equals( r.get(2)) && rc.equals( r.get(3) ) )

{ return r.get( 0 ); }

}
throw new NotFoundException( "no tile found" );