1st you have to run GetCompanyKey() function then InitReinitializeFiles() as these setup up some internal VARs that ReinitializeFile() needs.
Here's a ProvideX example I whipped up for reinit'ing AP_InvoiceHeader from SYZCON.
I presume you're using BOI or Customizer script. You can adapt for BOI (maybe you know how to do already) by changing syntax and a few things. Substitute NEW line with NewObject equivalent, the ' symbol with a . the %SYS_SS with oSS version. Also set all the preliminary stuff (nSetUser, nSetCompany, oSS, blah blah)
! ------------------------------------------------------
DROP OBJECT o,ERR=*NEXT
tmpModCode$=""AP"",tmpEverest$=""Y"",myFile$=""AP_INVOICEHEADER""
o=NEW(""SY_Reinitialize_bus"",%SYS_SS)
retVal=o'GetCompanyKey(%SYS_SS'CompanyCode$, tmpCompanyKey$, tmpCompanyObj)
retInit=o'InitReinitializeFiles(tmpModCode$,tmpEverest$)
retReinit=o'ReinitializeFile(myFile$)
! ------------------------------------------------------