HTTP/1.1 415 不支持的媒体类型 Excel 文件 Dawnload 问题

我在 silverlight 目录中有 Excel 导出功能。 用户右键单击目录，这将触发通过浏览器的下载。

public static void ExportValues(CatalogData data)
    {
        var excelData = new ExcelData
        {
            Sheets = new[] { data }
        };

        string serializedData = excelData.Serialize();
        HtmlPage.Window.Invoke("exportToExcel", serializedData);
    }

这是 JavaScript 调用

function exportToExcel(serializedData) {
var formId = "exportToExcelForm";
var inputId = "SerializedExcelData";

var form = document.getElementById(formId),
    input;
if (form == null) {
    form = document.createElement("form");
    form.setAttribute("id", formId);
    form.setAttribute("method", "POST");
    form.setAttribute("action", "../api/excel");
    form.style.visibility = "hidden";
    form.style.height = "0px";
    form.style.width = "0px";
    form.style.borderWidth = "0px";
    document.body.appendChild(form);

    input = document.createElement("input");
    input.setAttribute("id", inputId);
    input.setAttribute("type", "hidden");
    input.setAttribute("name", inputId);
    form.appendChild(input);
} else {
    input = document.getElementById(inputId);
}
input.setAttribute("value", serializedData);
form.submit();
input.setAttribute("value", "");

}`

[HttpPost]
public static HttpResponseMessage GenerateExcel(ExcelDataWrapper wrapper)
    {
        ExcelData data = wrapper.Unwrap();
        var content = new StreamContent(ExcelCreator.Create(data));
        var clientDateTime = ExcelCreator.ClientDateTime;
        var fileName = "test.xlsx";
        content.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment") { FileName = fileName };
        content.Headers.ContentType = new MediaTypeHeaderValue("application/vnd.openxmlformats-officedocument.spreadsheetml.sheet");

        return new HttpResponseMessage(HttpStatusCode.OK) { Content = content };           
 }

问题是，当部署到 IIS 服务器时，我收到错误 HTTP/1.1 415 不支持的媒体类型，请参阅 Fiddler

This code is running perfectly on my machine (Localhost)

无法找到这里出了什么问题