composing many quotations into linq queries

Question

I'm working on a project in which I'm trying to use F# and Linq for UDF's and stored procs in an SQL server. Part of that has been to statically define all the valid queries, the sorting criteria, and a means of scoring the results of the queries.

I've so far been fairly successful, but I'm running into serious difficulty composing sortBy expressions.

Here's the basic concept

let sorter =
    let exprMap:Map<string,Quotations.Expr<seq<Product> -> seq<Product>>> =
    Map.ofList
    ["ProductName",<@ Seq.sortBy (fun prod -> prod.Name) @> ]
    // .. more entries ..
    let sortBuilder sortkeys = 
        Array.foldBack 
         (fun criteria acc -> <@ %(exprMap.[criteria]) >> (%acc) @>)
         sortkeys
         <@ Seq.map id @>

This ends up being used later in the query executor like so

let execQuery = fun (predicates,sorts,scorer) ->
    <@ seq { for prod in (%dc).Products do
              if (%predicates) prod then yield prod }
       |> (%sorts)
       |> (%scorer) @> 

Using these basic outlines, everything works as long as I don't use (%sorts). Each time I pass that in, I get not recognized in F# to Linq translator. I've tried a number of different attempts at using combinators, but I have the sense I'm missing something. If I stub out the sorter function with the following

<@ Seq.sortBy (fun prod -> prod.Name) |> Seq.sortBy (fun prod -> prod.Style) @>

It works as expected. However using a combinator like this:

let (|>*) = fun f g -> <@ fun c -> ((%f) c) |> (%g) @>

does not..

Any ideas?