Crash with RooSimultaneous plus weight variable

I’m writing to report a crash that happens when using RooSimultaneous on a dataset that has a weight variable.
I’m using roofit version 5.26.00
It doesn’t happen if I remove the weight variable.
It doesn’t happen when I use an ordinary Pdf (even with a weight variable).
The backtrace is reported below.
Is there any workaround to use a weight variable in RooSimultaneous?
Many thanks in advance
Giulio

#9
#10 0x00c03c4a in strcmp () from /lib/libc.so.6
#11 0xf79f0d14 in TClass::InheritsFrom(char const*) const ()
from /raid/cmsadmin/cmssw/slc5_ia32_gcc434/lcg/root/5.22.00d-cms19/lib/libCore.so
#12 0xf796a873 in TObject::InheritsFrom(char const*) const ()
from /raid/cmsadmin/cmssw/slc5_ia32_gcc434/lcg/root/5.22.00d-cms19/lib/libCore.so
#13 0xf1b655da in RooTreeDataStore::get(int) const ()
from /raid/cmsadmin/cmssw/slc5_ia32_gcc434/cms/cmssw/CMSSW_3_6_3/external/slc5_ia32_gcc434/lib/libRooFitCore.so
#14 0xf1b64ec0 in RooTreeDataStore::cacheArgs(RooAbsArg const*, RooArgSet&, RooArgSet const*) ()
from /raid/cmsadmin/cmssw/slc5_ia32_gcc434/cms/cmssw/CMSSW_3_6_3/external/slc5_ia32_gcc434/lib/libRooFitCore.so
#15 0xf19a234f in RooAbsData::cacheArgs(RooAbsArg const*, RooArgSet&, RooArgSet const*) ()
from /raid/cmsadmin/cmssw/slc5_ia32_gcc434/cms/cmssw/CMSSW_3_6_3/external/slc5_ia32_gcc434/lib/libRooFitCore.so
#16 0xf19b6a78 in RooAbsOptTestStatistic::optimizeConstantTerms(bool) ()
from /raid/cmsadmin/cmssw/slc5_ia32_gcc434/cms/cmssw/CMSSW_3_6_3/external/slc5_ia32_gcc434/lib/libRooFitCore.so
#17 0xf19b6e01 in RooAbsOptTestStatistic::constOptimizeTestStatistic(RooAbsArg::ConstOpCode) ()
from /raid/cmsadmin/cmssw/slc5_ia32_gcc434/cms/cmssw/CMSSW_3_6_3/external/slc5_ia32_gcc434/lib/libRooFitCore.so
#18 0xf19eda27 in RooAbsTestStatistic::constOptimizeTestStatistic(RooAbsArg::ConstOpCode) ()
from /raid/cmsadmin/cmssw/slc5_ia32_gcc434/cms/cmssw/CMSSW_3_6_3/external/slc5_ia32_gcc434/lib/libRooFitCore.so
#19 0xf19b6bec in RooAbsOptTestStatistic::constOptimizeTestStatistic(RooAbsArg::ConstOpCode) ()
from /raid/cmsadmin/cmssw/slc5_ia32_gcc434/cms/cmssw/CMSSW_3_6_3/external/slc5_ia32_gcc434/lib/libRooFitCore.so
#20 0xf1ad175a in RooMinuit::optimizeConst(bool) ()
from /raid/cmsadmin/cmssw/slc5_ia32_gcc434/cms/cmssw/CMSSW_3_6_3/external/slc5_ia32_gcc434/lib/libRooFitCore.so
#21 0xf19c4565 in RooAbsPdf::fitTo(RooAbsData&, RooLinkedList const&) ()
from /raid/cmsadmin/cmssw/slc5_ia32_gcc434/cms/cmssw/CMSSW_3_6_3/external/slc5_ia32_gcc434/lib/libRooFitCore.so
#22 0xf19be048 in RooAbsPdf::fitTo(RooAbsData&, RooCmdArg, RooCmdArg, RooCmdArg, RooCmdArg, RooCmdArg, RooCmdArg, RooCmdArg, RooCmdArg) ()
from /raid/cmsadmin/cmssw/slc5_ia32_gcc434/cms/cmssw/CMSSW_3_6_3/external/slc5_ia32_gcc434/lib/libRooFitCore.so
#23 0xf16d750b in G__G__RooFitCore1_598_0_26(G__value*, char const*, G__param*, int) ()
from /raid/cmsadmin/cmssw/slc5_ia32_gcc434/cms/cmssw/CMSSW_3_6_3/external/slc5_ia32_gcc434/lib/libRooFitCore.so
#24 0xf6fa32b6 in Cint::G__ExceptionWrapper(int ()(G__value, char const*, G__param*, int), G__value*, char*, G__param*, int) ()
from /raid/cmsadmin/cmssw/slc5_ia32_gcc434/lcg/root/5.22.00d-cms19/lib/libCint.so

I made a little progress on this issue and compiled roofit wit debug symbols.
I found that the crash happens on line 684 of roofitcore/src/RooTreeDataStore.cxx:684
The code nes look like:

} else if (_wgtVar) {

// Otherwise look for weight variable
_curWgt = _wgtVar->getVal() ;  <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< HERE
_curWgtErrLo = _wgtVar->getAsymErrorLo() ;
_curWgtErrHi = _wgtVar->getAsymErrorHi() ;
_curWgtErr   = _wgtVar->hasAsymError() ? ((_wgtVar->getAsymErrorHi() - _wgtVar->getAsymErrorLo())/2)  : _wgtVar->getError() ;

Thanks for any help you can provide.
Giulio