The TP.root shows that 4 trees are merged. However, while scanning only the...

The TP.root shows that 4 trees are merged. However, while scanning only the last tree entries are shown 

Time walk correction/TreeTest.C

-//TList* TPlist = new TList;
+//TFile* TPfile = new TFile("TP.root","update");
+TList* TPlist = new TList;
 
 void TreeEnergyWrite(){
 
@@ -42,8 +43,8 @@ void TreeTPWrite(int c, int r){
   TFile* TPfile = new TFile("TP.root","update"); 
   std::string TPtreeName = "TPtree" + std::to_string(c) + "_" + std::to_string(r); 
   TTree* TPtree = new TTree(TPtreeName.c_str()," TP tree");
-  TTree* Mergedtree = new TTree("MergedTree", "Merged trees");
-  Mergedtree->SetDirectory(TPfile);
+  // TTree* Mergedtree = new TTree("MergedTree", "Merged trees");
+  // Mergedtree->SetDirectory(TPfile);
   
   TPtree->Branch("TPcol1",&TPcol1,"TPcol1/I");
   TPtree->Branch("TPcol2",&TPcol2,"TPcol2/I");
@@ -92,15 +93,21 @@ void TreeTPWrite(int c, int r){
 
   // TPtree->Write("",TObject::kOverwrite);
   // TPtree->Write("",TObject::kWriteDelete);
-  TPtree->Write();
-  //  TPtree->Scan();
+  // TPtree->Write();
+  // TPtree->Scan();
 
   //Add new trees (incl voltage col) to list and merge the trees
-  /* std::cout << " The tree for the pixel " <<  c <<  " and " << r << " is added to the list " << std::endl;
-  TList* TPlist = new TList;
+
+  //TList* TPlist = new TList;
+  std::cout << " The tree for the pixel " <<  c <<  " and " << r << " is added to the list " << std::endl;
   TPlist->Add(TPtree);
-  Mergedtree = TTree::MergeTrees(TPlist); 
-  Mergedtree->Write("",TObject::kWriteDelete);*/
+  TTree* newtree = TTree::MergeTrees(TPlist);
+  newtree->SetName("MergedTree");
+  //  TTree* Mergedtree = new TTree("MergedTree", "Merged trees");
+  newtree->SetDirectory(TPfile);
+  // Mergedtree = TTree::MergeTrees(TPlist); 
+  // Mergedtree->Write("",TObject::kWriteDelete);
+   newtree->Write("",TObject::kWriteDelete);
 
   TPfile->Close();
   //Efile->Close();
@@ -118,7 +125,7 @@ void TreeTest(){
     }
   }
 
-  // std::cout <<" The size of the tree list is " << TPlist->GetSize() << std::endl;
+  std::cout <<" The size of the tree list is " << TPlist->GetSize() << std::endl;
   //TPfile->Close();
 
 }