the email type must be one of: "html" or "text"

Mar 16, 2016 at 6:47 PM
I am getting this error when I am trying to update an existing member.
I don't get this error when the email address is new.
    Dim mcapi As MailChimp.MCApi
    mcapi = New MailChimp.MCApi(ApiKey, False)

    Dim Batchsubscribe As MailChimp.Types.List.BatchSubscribe
    Dim merges(SubscriberList.Count) As MailChimp.Types.List.Merges
    'Dim SubscribeOptions As New MailChimp.Types.List.SubscribeOptions

    Dim SubscribeCount As Int64 = 0

    Dim batch As List(Of Dictionary(Of String, Object)) = _
    New List(Of Dictionary(Of String, Object))
    For Each sub_rec As Subscribers In SubscriberList
        Dim entry As New MailChimp.Types.List.Merges
        entry.Add("EMAIL_TYPE", sub_rec.email_type)
        entry.Add("FNAME", sub_rec.fname)
        entry.Add("LNAME", sub_rec.lname)
        entry.Add("MMERGE3", sub_rec.CONTACT_NUMBER)
        entry.Add("MMERGE4", sub_rec.ROLE_C)
        entry.Add("MMERGE5", sub_rec.Enrolled_in_me)
        entry.Add("MMERGE6", sub_rec.newsletter)
        entry.Add("MMERGE7", sub_rec.nutrition)
        entry.Add("MMERGE9", sub_rec.intimacy)

        merges(SubscribeCount) = entry
        SubscribeCount = SubscribeCount + 1
    ' execution
    Dim SubscribeOptions As New MailChimp.Types.List.SubscribeOptions()
    SubscribeOptions.EmailType = MailChimp.Types.List.EmailType.Text
    SubscribeOptions.DoubleOptIn = False
    SubscribeOptions.UpdateExisting = True
    SubscribeOptions.ReplaceInterests = False
    SubscribeOptions.SendWelcome = False
    Batchsubscribe = mcapi.ListBatchSubscribe(LisID, merges, SubscribeOptions)
Thank you