The DocBegin macro is triggered just prior to opening an existing document (project). The DocBegin macro is executed by:

The DocBegin macro is unique in that a define statement for the DocBegin macro is contained in the file ORGSYS.CNF (found in the Origin software folder) which gets executed when projects are opened. Since ORGSYS.CNF is executed just prior to the triggering moment for DocBegin, you must either comment out this definition or modify it to define DocBegin as you wish. Otherwise, the default definition of DocBegin (which happens to do nothing) will be the one that gets executed upon being triggered.