Because there solution is wrong. I cannot even run some program. The program will loop forever.
for example:
If I have this definition:
// Copyright (c) 2013-2014 K Team. All Rights Reserved.
/*
Expected:
'ListWrap(1,,1,,1)
*/
module LABEL-AND-CONTEXT
  configuration <k> $PGM:K </k>

  syntax KLabel  ::= "'ListWrap" | "'A"
  syntax KResult ::= Int
  context 'ListWrap(_,,HOLE,,_)

  rule 'A(_) => 1
endmodule

and run this program:
'ListWrap('A(.KList),,'A(.KList),,'A(.KList))