I facing a problem here, why always skip my user input part and direct show that no row selected, but when I set a fixed input will come out the data? - sqlplus

Question

This is my code, please take a look
I want to get total number of student of fail, pass, merit and distinction in semester, so i need to input particular semesterid to get the result, but sqlplus always ignore and show the result no row selected.
column course_name format a50
compute sum label 'TOTAL_STUDENTS' of fail on report
compute sum label 'TOTAL_STUDENTS' of pass on report
compute sum label 'TOTAL_STUDENTS' of merit on report
compute sum label 'TOTAL_STUDENTS' of distinction on report
TTITLE CENTER "LEARNER_SEMESTER_RESULT_ANALYSIS"
break on report
create or replace view pass_result as
SELECT c.coursename as course_name, sc.courseID as courseID, count(r.learnerid) as num_of_students, sc.semesterid
FROM semestercourse sc, assessment a, result r, course c
WHERE sc.cs_id = a.cs_ID and
c.courseID = sc.courseID and
a.assesmentID = r.assesmentID and
r.status = 'Pass'
group by c.coursename, sc.courseID, sc.semesterid;
create or replace view fail_result as
SELECT sc.courseID as courseID, count(r.learnerid) as num_of_students, sc.semesterid
FROM semestercourse sc, assessment a, result r
WHERE sc.cs_id = a.cs_ID and
a.assesmentID = r.assesmentID and
r.status = 'Fail'
group by sc.courseID,sc.semesterid;
create or replace view merit_result as
SELECT sc.courseID as courseID, count(r.learnerid) as num_of_students,sc.semesterid
FROM semestercourse sc, assessment a, result r
WHERE sc.cs_id = a.cs_ID and
a.assesmentID = r.assesmentID and
r.status = 'Merit'
group by sc.courseID,sc.semesterid;
create or replace view distinction_result as
SELECT sc.courseID as courseID, count(r.learnerid) as num_of_students,sc.semesterid
FROM semestercourse sc, assessment a, result r
WHERE sc.cs_id = a.cs_ID and
a.assesmentID = r.assesmentID and
r.status = 'Distinction'
group by sc.courseID,sc.semesterid;
prompt Enter semester ID :
accept v_sid char
SELECT p.course_name, f.num_of_students as fail, p.num_of_students as pass,m.num_of_students as merit,d.num_of_students as distinction
FROM fail_result f
INNER JOIN pass_result p ON f.courseID = p.courseID and f.semesterID = p.semesterID
INNER JOIN merit_result m ON f.courseID = m.courseID and f.semesterID = m.semesterID
INNER JOIN distinction_result d ON f.courseID = d.courseID and f.semesterID = d.semesterID
where d.semesterID = '&v_sid';