Pass Date Problem Get Data Is Not Perfect ?

select reg.RegID,reg.FName+' '+reg.MName+' '+reg.Surname as PatientName,reg.MName+' '+reg.Surname as PtName,reg.PAddress,
    CONVERT(char(10),reg.BDate,103)as BDate,(DATEDIFF(YEAR, reg.BDate, GETDATE())) AS Age,
    case when CONVERT(char(10),reg.MarriageDate,103)='01/01/1900' then '-' else
    (DATEDIFF(YEAR, reg.MarriageDate, GETDATE())) end as MrgYear ,
    CONVERT(char(10),reg.MarriageDate,103)as MarriageDate,reg.Religion,reg.BloodGroup,
    reg.HeighttFt,reg.HeightInc,reg.PWeight,
    reg.Mobile,reg.Mail,reg.Gender,reg.Occupation,reg.RegistrationFor,
    logi.Password,CONVERT(char(10),reg.EntryDate,103) as EntryDate,ad.Name as CityName
  from RegistrationMst reg left outer join LoginMst logi on (reg.RegID=logi.UserID)
  inner join AddressMst ad on (reg.CityID=ad.SrNo)
  where reg.IsActive=1
  and (reg.RegID=@RegID or @RegID=-1)
  and (reg.Mobile like '%'+ @Mobile +'%' or @Mobile='')



   and ((CONVERT(char(10),reg.EntryDate,103) between (CONVERT(char(10),@FromDate,103)) and CONVERT(char(10),@ToDate,103)) or

 (CONVERT(char(10),@FromDate,103)='01/01/1900' and CONVERT(char(10),@ToDate,103)='01/01/1900'))