Highlight blank cell in a selected range of a sheet

Sub Highlight_Cell()
Dim Rng As Range

For Each Rng In Range("A2:H20") 
If Rng.Value = "" Then
Rng.Interior.ColorIndex = 6 ‘yellow
Else
Rng.Interior.ColorIndex = 0 'blank
End If
Next Rng
MsgBox "Please fill in all mandatory fields highlighted in yellow."
End

CURRENTLY I AM USING THIS CODE BUT IT DOES NOT STOP AT THE LAST ROW OF DATA ENTRY

PLZ HELP

Dim ws As Workbook
Dim rng1 As Range
Dim rng2 As Range
bCheck = False
'works on sheet 1, change as needed
Set rng1 = ws.Range("B7:I51000").Find("*", ws.[b7], xlValues, xlWhole, xlByRows)
If rng1 Is Nothing Then
    MsgBox "DATA IS COMPLETE " & " YOU CAN PROCEED", vbCritical
    Exit Sub
End If
Set rng2 = ws.Range(ws.[b7], ws.Cells(rng1.Row, "I"))
On Error Resume Next
Set rng2 = rng2.SpecialCells(xlBlanks)
On Error GoTo 0
If rng2 Is Nothing Then Exit Sub
bCheck = True
rng2.Interior.Color = vbYellow
MsgBox "Please fill in all mandatory fields on " & ws.Name & " highlighted in yellow", vbCritical, "Save Cancelled!"
Application.Goto rng2.Cells(1)
End Sub

THIS IS ANOTHER TRY BUT THAT IS ALSO NOT WORKING FINE

PLZ HELP SO THAT WITH THE ACTIVE SHEET AND WITHIN A SPECIFIED RANGE ALL THE BLANK CELLS CAN BE HIGHLIGHTED WITH YELLOW COLOR WITH THE MSG THAT FILL ALL YELLOW COLORED CELLS

BUT THIS SHOULD BE UPTO LAST DATA ENTRY ROW....

My data will be with in b7 to i510000

plz help...