Error converting data type nvarchar to date

Good evening I have a problem registering a form of a dating system in which marks the error of the title, I think the solution would be to convert the following code.

Private Sub BtnRegistrar_Click(sender As Object, e As EventArgs) Handles BtnRegistrar.Click
        If Me.ValidateChildren = True And TxtDescripcion.Text <> "" And cmbpacientes.Text <> "" And cmbagendo.Text <> "" And cmbespecialistas.Text <> "" Then
            Try
                reg.descripcion = TxtDescripcion.Text
                reg.FechaCITA = Convert.ToDateTime(Calendario.Value)
                reg.paciente = cmbpacientes.Text
            If cmbpacientes.SelectedItem = "Enfermito1" Then
                reg.paciente = "Enfermito1"
            ElseIf cmbpacientes.SelectedItem = "Enfermito2" Then
                reg.paciente = "Enfermito2"
            End If


            If cmbagendo.SelectedItem = "Recepcionista1" Then
                reg.agendo = "Recepcionista1"

            ElseIf cmbagendo.SelectedItem = "Recepcionista2" Then
                reg.agendo = "Recepcionista2"

            End If

            If cmbespecialistas.SelectedItem = "Simi" Then
                reg.especialista = "Simi"

            ElseIf cmbespecialistas.SelectedItem = "LatinLover" Then
                reg.especialista = "LatinLover"

            End If

            If func.REGISTRAR_CITA(reg) Then
                MessageBox.Show("Cita registrada correctamente", "Guardando cita")
            End If
        Catch ex As Exception
            MsgBox(ex.Message)
        End Try
    Else
        MessageBox.Show("Debe llenar todos los campos", "Guardando cita", MessageBoxButtons.OK, MessageBoxIcon.Information)
    End If
End Sub

Any comments are valid to be able to finish this catalog:)