Computing Grade

[Simply Me]

Hi!

I am using SP and part of which is to get the average of a certain subject...I am doing it like

UPDATE tblgrade
SET [MAPEH] =((MUSIC * .25) + (ARTS * .25) + (PE * .25) + (HEALTH * .25))
FROM tblenrol
WHERE tblGrade.IDNO = tblenrol.IDNO
AND tblGrade.yearlevel = tblenrol.yearlevel
AND tblenrol.SubjectName like 'MUSIC%'
AND tblenrol.SubjectName like 'ARTS%'
AND tblenrol.SubjectName like 'PE%'
AND tblenrol.SubjectName like 'HEALTH%'

but I am not getting any result at all so I tried doing it like

UPDATE tblgrade
SET [MAPEH] =((tblenrol.SubjectName like 'MUSIC%' * .25) + (ARTS * .25) + (PE * .25) + (HEALTH * .25))
FROM tblenrol
WHERE tblGrade.IDNO = tblenrol.IDNO
AND tblGrade.yearlevel = tblenrol.yearlevel
AND tblenrol.SubjectName like 'MUSIC%'
AND tblenrol.SubjectName like 'ARTS%'
AND tblenrol.SubjectName like 'PE%'
AND tblenrol.SubjectName like 'HEALTH%'

but still its not correct. it's a syntax error.

Music, Arts, PE, and Health are subjects in my other table. I had them converted as fields in the table where I would like to have the Final grade to appear.
here's part of my SP

CREATE TABLE [dbo].[tblGrade](
	[IDNo] [nvarchar](10) NOT NULL,
	[LastName] [nvarchar](50) NULL,
	[FirstName] [nvarchar](50) NULL,
	[MI] [nvarchar](50) NULL,
	[Reading] [numeric](5, 0) NULL,
	[Language] [numeric](5, 0) NULL,
	[English] [numeric](5, 0) NULL,
	[Math] [numeric](5, 0) NULL,
	[Music] [numeric](5, 0) NULL,
	[Arts] [numeric](5, 0) NULL,
	[PE] [numeric](5, 0) NULL,
	[Health] [numeric](5, 0) NULL,
	[MAPEH] [numeric](5, 0) NULL,

I hope, I explained it clearly. Anyone can help me please?