Debug renderer not working

I have created a debug renderer

for a Calendar using the following expression: DateFormat.getDateTimeInstance().format(this.getTime())

this works fine on my home system (64 bit JVM, Windows 7) but gives the following error on WinXP 32 bit, 32 bit JVM, all jdk1.6.0_18:

• startTime = {java.util.GregorianCalendar@261}unable to evaluate the expression Cannot find local variable 'DateFormat'

Can anyone tell me what is happending, if not, should I submit a bug.  Serge, HELP!