Rule fires unexpectedly - not CE fails

The rule shown below fires, and then the code on the RHS prints "But cell ... matches" which is only possible when there is a Cell according to the constraints in the "not" CE. - The full Sudoku code is available.

rule "column elimination"
when
not Setting()
$i: Integer()

1. occurs in a Cell
   $c: Cell( free contains $i, $cs: cellSqr, $cc: cellCol )
2. but not in another cell of the same square and a different column
   not Cell( this != $c, free contains $i, cellSqr == $cs, cellCol != $cc )

1. 1. not ( $oc: Cell( this != $c )
   2. and
   3. eval( $oc.getFree().contains( $i ) &&
   4. $oc.getCellSqr().equals( $cs ) &&
   5. ! $oc.getCellCol().equals( $cc ) ) )
2. but there is a cell in the same column and another square containing this value
   $cx: Cell( freeCount > 1, free contains $i, cellCol == $cc, cellSqr != $cs )
   then
3. remove the value from that other cell
   System.out.println( "column elimination due to " + $c.posAsString() +
   ": remove " + $i + " from " + $cx.posAsString() );

for( int iRow = 0; iRow < 9; iRow++ ){
for( int iCol = 0; iCol < 9; iCol++ ){
Cell cell = Sudoku.sudoku.cells[iRow][iCol];
if( ! cell.equals( $c ) &&
cell.getCellSqr().equals( $cs ) &&
! cell.getCellCol().equals( $cc ) &&
cell.getFree().contains( $i ) )

{ System.out.println( "But cell " + cell.toString() + " matches!" ); }

}
}

for( Cell c: $cs.getCells() )

{ System.out.print( c.posAsString() + ": " + c.getFree() + " cc="+c.getCellCol() + " cs="+c.getCellSqr() + "; " ); }

System.out.println();

modify( $cx )

{ blockValue( $i ) }

end