[ns] ns 2.26 error

[Sharath]

i had written a script which runs well with ns 2.27 perfectly but is not
running on ns 2.26.....
its giving the following error...cant understand what this means
pleas help
#  ./ns sjg.tcl -nn 50 -stoptime 20 -packetsize 1000 -rtsthreshold 3000
-expdelay 0.1s
ns:
[code omitted because of length]
: no instvar in global :: scope
    (Object instvar line 1)
    invoked from within
"$self instvar id"
    (procedure "SplitObject" line 2)
    (SplitObject getid line 2)
    invoked from within
"SplitObject getid"
    (procedure "new" line 2)
    invoked from within
"new RNG"
    invoked from within
"set defaultRNG [new RNG]"


-sharath