c# razor : Check Box for decimal typed data making error

If I delete line Line 15 in this partial view there is no error. If i replace ORGANIZATION_NO by TRAINER_NO that is also making an error. I don't understand that why if I want to make any checkbox for a value that is decimal (in database table column) making an error. But for string typed value error is not occurring.

       @model List<EMIS_BY_ME.Models.Viewmodel>
        @{
            Layout = null;   
        }        
       @foreach (var item in Model )
         { 
          Line 14:  @item.TRAINER_VIEWMODEL.MOBILE_NUM
          Line 15: @Html.CheckBox(item.ORGANIZATION_VIEWMODEL.ORGANIZATION_NO)
          Line 16: @Html.CheckBox(item.ORGANIZATION_VIEWMODEL.ORGANIZATION_NAME)

        }

Compiler Error Message: CS1928: 'System.Web.Mvc.HtmlHelper>' does not contain a definition for 'CheckBox' and the best extension method overload 'System.Web.Mvc.Html.InputExtensions.CheckBox(System.Web.Mvc.HtmlHelper, string)' has some invalid arguments

Source Error: