Conversion failed when converting date and/or time from char

Question

I m grtting this error for some students only. Most of students book their appointment ok.

Y is this .

 

 

Conversion failed when converting date and/or time from character string

 this is my sql.

 

select @CAMPUS_ID=(SELECT CAMPUS_ID

FROM Bk_VwStudentWithCampus

WHERE (studentID = @studentID))

SELECT BK_tblPeriod.PeriodNo, BK_tblPeriod.PeriodName, Bk_tblWeekPeriod.CampusID FROM BK_tblPeriod INNER JOIN Bk_tblWeekPeriod ON BK_tblPeriod.PeriodNo = Bk_tblWeekPeriod.PeriodNo INNER JOIN BK_tblCurrentWeek ON Bk_tblWeekPeriod.WeekNo = @WeekNo

where CampusID = @CAMPUS_ID