reconstructed variables

Hello ROOTers,

I am trying to create a new file containing  variables from a file I already have. I'm putting in this new file only the variables I need and I'm trying to put some reconstructed variables too. My script (attached) executes and the original variables are OK, but when I look into those reconstructed variables, they aren't filled, that means it returns zero for all of them, although they have 1000 entries. I think that the expressions for those variables aren't being read. Anybody know what am I doing wrong?

I also tried
"for (Int_t i = 0; i<nentries; i++) {
   T.GetEntry(i);"

instead of using SetAlias. But when I do this, the scripts does not execute completely because it doesn't recognize the variables I already have in the expression of the reconstructed variables. For example "particle..Px".

Thank you,

Michelle.