Keep Coding

I've written a NEST query that matches documents that have words in a string ("queryString" below). I want to filter out documents that contain the word "not". I've tried the boolean query but it doesn't filter out the documents. What am I doing wrong here?
var searchResponse2 = _EsClientDAL.Current.Search<DTO.riSmall>(s => s
.Size(50)
.Query(q => q
.Bool(b => b
.Must(mu => mu
.Match(m => m
.Field(f => f.SceneText)
.Query(queryString)
)
,
mu => !mu
.Term(p => p.SceneText, "not")
)
)
)
.Highlight(h => h
.PreTags("|")
.PostTags("|")
.Fields(
fs => fs
.Field(p => p.SceneText)
.Type("plain")
.ForceSource()
.FragmentSize(150)
.NumberOfFragments(3)
.NoMatchSize(150)
)
)
);

you can try with following query using must_not
Query(q => q
.Bool(b => b
.Must(mu => mu
.Match(m => m
.Field(f => f.SceneText)
.Query(queryString)
)
)
.MustNot(mn=> mn
.Term(p => p.SceneText, "not")
)
)
)
Hope this helps you