Async webform and globalization

I have an async webform with globalization.

Code:

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<%@ Page Async="true" ...

---

Code:

---

      protected override void InitializeCulture() {       
        string culture = "";

        if (Request.QueryString["ci"] != null)
            culture = Request.QueryString["ci"];

        System.Globalization.CultureInfo ci = new System.Globalization.CultureInfo(culture);
        System.Threading.Thread.CurrentThread.CurrentCulture = ci;
        System.Threading.Thread.CurrentThread.CurrentUICulture = ci;

        base.InitializeCulture();
      }

---

In this page, I have a gridview. The datasource of the gridview is some data of a 3th party webservice. This webservice is invoked async. When I open this page with Dutch cultureInfo, I've noticed that all is in Dutch, except the content of the Gridview (except the headers).

After debugging I found out that in the gridview's RowDataBound event the System.Threading.Thread.CurrentThread.CurrentCulture is reset to 'en-US'.

Any idea why this happens and how to prevent this from happening?