IE11中的KnockOut绑定问题

Question

我有一个KnockOut视图模型

viewModel = {
    // Observables
    insuredPersonList: ko.observableArray(),
    premiumFrequency: ko.observable(initialData.premiumFrequency),
    monthlyType: ko.observable(getMonthlyTypeFromInitialData()),
    includeCareClause: ko.observable(initialData.includeCareClause),
    nrOfInsuredChildren: ko.observable(initialData.nrOfInsuredChildren),
    hasValidResponse: ko.observable(false),
    currentCalculations: ko.observable(0),
    firstname: ko.observable(initialData.firstname),
    lastname: ko.observable(initialData.lastname),
    email: ko.observable(initialData.email),
    birthday: ko.observable(initialData.birthday),
    producerAccount: ko.observable(initialData.producerAccount),
    delaSiteType: ko.observable(initialData.delaSiteType),
    userid: ko.observable(initialData.userid),
    language: ko.observable(initialData.language)
}

在代码的一部分中，我试图将文本框的值绑定到observable。问题是它适用于IE 8,9,10，Chrome，Firefox，但不适用于IE11。

<asp:TextBox CssClass="inputfield M numbersOnly" runat="server" ID="txtPremiumInsured1" 
data-bind="value: insuredPersonList()[0].premium, enable: monthlyType() == 'premium'" />