"Form dataItem which is intended to update does not exist."

I want to retrieve a data row (from the Recorded data table of the form) and load it to the bizform.

I have this code in my web part:

protected override void OnLoad(EventArgs e)
{
    ...
    QueryMacros macros = new QueryMacros();
    macros.Where = String.Format("(UserID = '{0}') AND (UniGridID = '{1}')",
    CMS.Membership.MembershipContext.AuthenticatedUser.UserID, UniGridID);
    DataSet dsFilterForm = connection.ExecuteQuery(dataAlterClassinfo.ClassName + ".selectall", null, macros);
    if (dsFilterForm.Tables[0].Rows.Count != 0 && dsFilterForm.Tables[0].Rows[0][0] != null)
    {
        int formRecordId = ValidationHelper.GetInteger(dsFilterForm.Tables[0].Rows[0][0], 0);
        viewBiz.ItemID = formRecordId;
        viewBiz.ReloadData();
    }

formRecordId loads correct ID which really exists however bizform doesn't update itself and displays this error string: "Form dataItem which is intended to update does not exist."