Modules & VBA :: Set Datatype As Date / Time In The Form - Update Table With Null Date

I have a form with Date of Death (DOD) field. I would like update DOD from a table dbo_patient into Z_Patients table.

I have set the datatype as Date/Time in the form for Date of Death.

Code:
Private Sub Update_DOD()
Dim rcMain As New ADODB.Recordset, rcLocalDOD As New ADODB.Recordset
Dim DOD As String
rcMain.Open "select distinct PatientKey from Z_Patients", CurrentProject.Connection

[Code] ....

However I am getting some error Run-time error '-2147217913 Date type mismatch in criteria expression in section below.

Code:
CurrentProject.Connection.Execute "update Z_MAIN_Processed_Patients set DateOfDeath = '" & rcLocalDOD!date_of_death & "' where PatientKey = " & !PatientKey