Nee macro to check values in each cell & give error message if the values crosses a number

Hi all,
Here's the table i am using:

A

B

C

D

E

F

G

H

I

J

K

L

1

EMP NO

1-Sept

2-Sept

3-Sept

4-Sept

5-Sept

6-Sept

Count of N

Count of A

Count of G

2

N

N

N

A

A

G

G

N

4

2

2

3

N

N

A

A

A

G

A

G

2

4

2

4

N

N

A

A

A

G

A

G

2

4

2

5

N

N

A

A

A

G

A

G

2

4

2

Columns J,K and L are the counts of Ns, As and Gs. Have used Count excel formula.

So my problem is this. I need to write a macro to check each value from J2 to L4. If the value in any of the cell in the range J2 to L4 goes beyond 3 it should give an error pop-up saying -"Error-Too many values". Note that the values in J2 to J4 keep changing when the values f N, A, and G changes in A1 to H4.

if i am entering, lets say N in row 1, if i give 3 Ns it shouldn't give me error. But the 4th N entry, once i enter it should give a pop up error. It can let me enter more than 3 Ns but every-time it crosses 3 it shoud give pop up.
Ex: Enter 1 N - no pop up
Enter 2nd N - no pop up
Enter 3rd N -no pop up
Enter 4th N - Pop up
Enter 5th N- Pop up
Enter 6th N - Pop up .

let me know the macro for this. As a noob i didnt get any proper solution for this. All i wrote was this. But its not of any use.

Option Explicit
Sub Abi()

Dim i As Range
For Each i In Range("J2:L4")
If i.Value > 2 Then
MsgBox "hello"
End If
Next i
End Sub

Hey davesexcel , Thanks for the reply. And sorry for the incomplete data.

I have attached the sheet which i have prepared. Also the things which needs to be done in there.

Basically its like this. For a particular employee, the max allowed shifts[N, A or G] are 3. If somebody tries to give him more than 3 shifts for a week, it should give an error pop-up saying "the maximum limit has crossed".

Let me know if any more clarity is needed.Trial.xlsm