order by column of linkentity

codes same like following:

var exp = new QueryExpression("table1"){

columnSet=...,

LinkEntities={

new LinkEntity("table1", "table2", "key1", "key2", oinOperator.Inner){

EntityAlias = "t",

Columns = ...

}

},

Orders = {

new OrderExpression("t.sortColumn", ...)

}

}

error message: "table1" entity doesn't contain attribute with Name='t.sortColumn'. 

but the column is exists.

I wonder to know how to resolve it. thanks.