Hi Markus,
you can't combine transactions and activities without checking authority objects.
In FB01 you will have several authority-checks for the same activity, for example:
AUTHORITY-CHECK OBJECT 'F_FAGL_SEG'
ID 'SEGMENT' FIELD LD_SEGMENT
ID 'GLRRCTY' FIELD I_RRCTY
ID 'ACTVT' FIELD I_ACTVT.
AUTHORITY-CHECK OBJECT 'F_BKPF_BLA'
ID 'ACTVT' FIELD I_ACTVT
ID 'BRGRU' FIELD I_BEGRU.
AUTHORITY-CHECK OBJECT 'F_BKPF_GSB'
ID 'ACTVT' FIELD i_actvt
ID 'GSBER' FIELD i_gsber.
AUTHORITY-CHECK OBJECT CHAR(10)
ID 'ACTVT' FIELD I_ACTVT
ID 'BRGRU' FIELD I_BEGRU.
AUTHORITY-CHECK OBJECT 'F_BKPF_KOA'
ID 'ACTVT' FIELD I_ACTVT
ID 'KOART' FIELD I_KOART.
AUTHORITY-CHECK OBJECT 'F_FAGL_LDR'
ID 'BUKRS' FIELD i_bukrs
ID 'GLRLDNR' FIELD ld_ledger
ID 'GLRRCTY' FIELD i_rrcty
ID 'GLRVERS' FIELD i_rvers
ID 'ACTVT' FIELD i_actvt.
AUTHORITY-CHECK OBJECT f_bkpf_buk
ID 'ACTVT' FIELD act_hinz
ID 'BUKRS' FIELD bkpf-bukrs.
They may all be processes for tcode FB01 and activity '01'. You need to have authorities on this activity for company code, account, ledger, business area and many more.
If you have authority for activity 01 for FB01 for all business areas, but for no company code, then you still can't use FB01.
Regards,
Klaus