Struggling with OrderBy Lambda expression

[Ginolard]

I'm getting my feet wet with Lambda expressions and it's rather overwhelming.

I have a UserPrincipal object called SelectedUser. I wish to get a sorted list of the user's groups

This is what I have so far but when I include that code my application's form flashes a few times and closes! Also, what is the significance of the "r" in the "Return From r" statement?

Dim SortedGroups As PrincipalSearchResult(Of Principal) = GetSortedGroups(Me.SelectedUser.GetGroups())

    Private Function GetSortedGroups(ByVal psp As PrincipalSearchResult(Of Principal)) As PrincipalSearchResult(Of Principal)
        Return From r In psp.OrderBy(Function(t) t.Name)
    End Function

[Ginolard]

Right, after some trial and error it's working. I had to cast it to an array

    Private Function GetSortedGroups(ByVal psp As PrincipalSearchResult(Of Principal)) As Principal()
        Return (From r In psp.OrderBy(Function(grp) grp.Name)).ToArray()
    End Function

Would someone mind explaining why this is so?

[kareninstructor]

Right, after some trial and error it's working. I had to cast it to an array

    Private Function GetSortedGroups(ByVal psp As PrincipalSearchResult(Of Principal)) As Principal()
        Return (From r In psp.OrderBy(Function(grp) grp.Name)).ToArray()
    End Function

Would someone mind explaining why this is so?

You need to cast it as an Array because your return type Principal() is an array.

[Ginolard]

No, I meant why does the function have to return an array? Originally I was trying to return a PrincipalSearchResult collection which, obviously, wasn't working.

LinQ is confusing

[kareninstructor]

No, I meant why does the function have to return an array? Originally I was trying to return a PrincipalSearchResult collection which, obviously, wasn't working.

LinQ is confusing

Did you try .ToList
In regards to confusing, only when you do not take time to learn it rather then simply using LINQ.