Error in <TKey::ReadObj>: Unknown class TTree

From: Reinhard Schwienhorst (schwier@mnhepw.hep.umn.edu)
Date: Sat Jan 29 2000 - 20:38:50 MET 

Hi,
I have run into a problem when reading trees from a file with a program
rather than in a macro. I am using the event example from the test area and
I have created the event.root file. I modified MainEvent.cxx and removed
everything in the write case ( the "else {" part of "if read == 1)").
I get the following output:
bash.exe-2.02$ Event 100 0 0 20
TFile**         Event.root
 TFile*         Event.root
  KEY: TH1F     htime;1 Real-Time to write versus time
  KEY: TTree    T;1     An example of a ROOT tree
  KEY: TH1F     hstat;1 Event Histogram
Error in <TKey::ReadObj>: Unknown class TTree

What is going on? How can TKey not know about TTrees?
Reading the tree works fine with the unmodified MainEvent.cxx routine. That
is puzzling, because I only removed parts that don't get called.

I am running on Windows NT with ROOT 2.23/11.

Thanks for any help,

Reinhard

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