Failure in TTree filling

Dear rooters,

sometimes, while filling a TTree, I encountered this message:

Error in <TTree::Fill>: Failed filling branch:matches.matches, nbytes=-1

can someone explain me what does it mean? What mistake did I do while creating the code to fill that TTree?
For completeness I must say that this TTree is filled with a branch made from a struct of primitive data types.

Thanks,

         Alberto

• Alberto Pulvirenti, Ph. D. ----- Universita' di Catania, Dipartimento di Fisica e Astronomia Via Santa Sofia, 64 I-95129, Catania, Italy

  Tel :+39-095-3785286