strange warning when using hadd

Hello,
when trying to add root files using hadd I got the following
warning message:

Warning in <TStreamerInfo::BuildCheck>:
        The StreamerInfo of class TArrayF read from file
DTTimeBoxes_first_43553_0.root
        has the same version (=1) as the active class but a
different checksum.
        You should update the version to
ClassDef(TArrayF,2).
        Do not try to write objects with the current class
definition,
        the files will not be readable.


Any idea of what the problem is? 

thanks,
                    Marina

Hi Marina,

Which version of ROOT are you using? 

Cheers,
Philippe.

-----Original Message-----
From: owner-roottalkroot.cern.ch [mailto:owner-roottalkroot.cern.ch] On
Behalf Of Marina Giunta
Sent: Friday, May 09, 2008 8:43 AM
To: roottalk (Mailing list discussing all aspects of the
ROOT system)
Subject: [ROOT] strange warning when using hadd

Hello,
when trying to add root files using hadd I got the following
warning
message:

Warning in <TStreamerInfo::BuildCheck>:
        The StreamerInfo of class TArrayF read from file
DTTimeBoxes_first_43553_0.root
        has the same version (=1) as the active class but a
different
checksum.
        You should update the version to
ClassDef(TArrayF,2).
        Do not try to write objects with the current class
definition,
        the files will not be readable.


Any idea of what the problem is? 

thanks,
                    Marina