copy selected entries of subset of chain

Hello ROOTTalk

I would like to copy selected entries of some branches of TChain to another tree. So far my attempt work for single tree but not for a chain. Simplified logic looks like this:

type var1;
TBranch * b1=0;
chain->SetBranchAddress("var1", &var1, &b)

chain->SetBranchStatus("*", 0)
chain->SetBranchStatus("var1", 1);

f = TFile::Open("file.root", "UPDATE");
newTree = chain->CloneTree(0);

now have to enable all branches since they are needed for event selection chain->SetBranchStatus("*", 0);
for(; ; )
 if(selection_function())

    newTree->Fill()

The trees are connected and when a new file is opened in chain things go wrong. I tried reseting the branch addresses, but it didn't work. Is there any way to get it working?

Thanks,

      Margar