Not able to find relation between assignment and Grade Step in BIP Query

Summary:

select PGSF.* from per_all_assignments_m PAAM, PER_GRADES_F PGD, PER_GRADE_STEPS_F PGS, PER_GRADE_STEPS_F_TL PGSF

where 

PAAM.GRADE_ID=PGD.GRADE_ID

AND PGD.GRADE_ID=PGS.GRADE_ID

and PGS.GRADE_STEP_ID=PGSF.GRADE_STEP_ID

and PAAM.person_id='100000008733781' 

and PAAM.LEGISLATION_CODE='CA'

and PGSF.LANGUAGE='US'

AND trunc(sysdate)between PAAM.effective_start_date and PAAM.effective_end_date

AND trunc(sysdate)between PGD.effective_start_date and PGD.effective_end_date

AND trunc(sysdate)between PGS.effective_start_date and PGS.effective_end_date