jsdIValue.getStringValue() encoding problem

(I can't sure what can I post this question here, sorry)

Environment:
Windows XP, Eclipse 3.4, xul runnenr 1.9, firefox 3.0.5

I developing remote java script debugger. When debugger suspends,
local varialble's value of current stackframe (retrieved as jsdiValue) 
returns broken string through getStringValue()

I tested Korean and Japanese, Only English seems okay.
The returned value is not just miss encoded, it lost it's own original 
UTF data.

Can anybody direct me right way?
Any information will help much!