Implicit string conversion is not supported when the alternate collating sequence is in effect for one of the comparison operands.
30
Cause . . . . . : If a comparison is attempted between a character operand and a UCS-2 or Graphic operand, the comparison is not supported if the character operand requires the alternate collating sequence.
Recovery . . . : Either specify ALTSEQ(*NONE) for the character operand, or explicitly convert the character operand using %UCS2 or %GRAPH.