Trouble with getting a checkbox to place a cell value when matching the textbox.

So I have a userform the has two textboxes and two checkboxes. The first textbox is the Guestname and the second is Roomnum. The two checkboxes are called MSbox and ONbox. When a user inputs the same username that is already there, the room number gets put into a separate column (up to 3 times).

What I am having trouble with is when the MSbox is true, then it puts a M/S in column F with the corresponding name if it already there.

Here is the current code for the MSbox:

If MSbox.Value = True Then
            Res = Application.Match(Guestname.Value, .Columns(2), 0)
                If Not IsError(Res) Then
                    emptyCol = Application.CountA(.Rows(Res).Range("F6:F38")) = "M/S"
                    emptyRow = Res
                Else
                    emptyRow = .Range("F" & Rows.Count).End(xlUp).Row + 1 = "M/S"
                End If
        End If

Here is the other code I have for the textboxes (there is more code, but I left some out to simplify it, here is what I have):

Private Sub SubmitButton_Click()

Dim emptyRow As Long
Dim emptyCol As Long
Dim Res As Variant
Dim ctl As Control
    
        If ONbox.Value = True Then
            Res = Application.Match(Guestname.Value, .Columns(15), 0)
                If Not IsError(Res) Then
                    MsgBox "Individual has had an overnight more than three times in a five month period. He/She is allowed back on: " & Range("P4"), vbOKOnly + vbCritical, "Overnight Ban"
                        Guestname.Value = ""
                        Roomnum.Value = ""
                        For Each ctl In Me.Controls
                        If TypeName(ctl) = "CheckBox" Then ctl.Value = False
                        Next ctl
                    Exit Sub
                End If
        Else
        
        End If
        If MSbox.Value = True Then
            Res = Application.Match(Guestname.Value, .Columns(2), 0)
                If Not IsError(Res) Then
                    emptyCol = Application.CountA(.Rows(Res).Range("F6:F38")) = "M/S"
                    emptyRow = Res
                Else
                    emptyRow = .Range("F" & Rows.Count).End(xlUp).Row + 1 = "M/S"
                End If
        End If

        Res = Application.Match(Guestname.Value, .Columns(2), 0)
        If Not IsError(Res) Then
            emptyCol = Application.CountA(.Rows(Res).Range("C1:E1")) + 3
            emptyRow = Res
            If emptyCol > 5 Then
                MsgBox "All 3 visits have been used"
                    Guestname.Value = ""
                    Roomnum.Value = ""
                    For Each ctl In Me.Controls
                    If TypeName(ctl) = "CheckBox" Then ctl.Value = False
                    Next ctl
                Exit Sub
            End If
        Else
            emptyRow = .Range("B" & Rows.Count).End(xlUp).Row + 1
        End If
        Cells(emptyRow, 2).Value = Guestname.Value
        Cells(emptyRow, emptyCol).Value = Roomnum.Value
    End With
    
    Unload Name_usrfrm

End Sub

I will also attach my workbook if you want to check it out.