Sheets("Bulk MO").Visible = True
Sheets("Bulk MO").Select
Sheets("Bulk MO").Unprotect
Dim lRow As Long
For lRow = 14 To 50 Step 3
If Cells(lRow, 1).Value = 0 Then
Rows(lRow & ":" & lRow + 2).EntireRow.Hidden = True
End If
Next
Sheets("Bulk MO").Protect
Sheets("Bulk MO").Visible = False


Gives an error:

Run-time error '1004':
Unable to set the Hidden property of the Range class