My Webpart does not see Field in a list

Question

I am writing a webpart for SharePoint 2007 and have 1 problem with accessing list by a webpart.

I have a list with lets say 10 fields and I am using this fields by a webpart without problem. But after adding new field to a list and trying to use it in a webpart i got exception about missing field.

To access list I am using LINQ like this:

listitems = (from SPListItem item in items
    where string.IsNullOrEmpty(Filter) || string.IsNullOrEmpty(item[FilterColumn] as string) || (item[FilterColumn] as string).Split().Contains(Filter.Trim())
    let url = GetUrl(item[ImageUrl] as string)
    let ext = item[IsExternal].ToString().ToLower() == "true"
    let linkUrl = GetUrl(item[LinkColumn] as string)
    let linkDescription = GetUrlDescription(item[LinkColumn] as string)
    let desc = item[ImageDescription] as string
    let alt = item[ImageAlt] as string
    select new CarouselItem() { ImageUrl = url, Link = linkUrl, LinkDescription = linkDescription, ImageAlt = alt, ImageDescription = desc}).ToList();

And problem exists in newly created column IsExternal.

Of course under properties "ImageUrl" etc are proper values.

I have checked also in couple of SharePoint tools this column and I can see it in CAML Query Viewer and other tools. Only my webpart does not see it.

Do you have any possible solution for this?