How can I get the sales filtered by KEY?

I am using the SDK, but I can't find how to filter by KEY use ID and/or KEY and it tells me that it is not possible

Dim m_salesList = oCompanyContext.Factories.SalesInvoiceFactory.List()

oFilterFact = FilterExpression.Equal(FilterExpression.Property("SalesInvoice.ID"), FilterExpression.Constant(sID))
oModifiers.Filters = oFilterFact

" Filtering or Sorting is not supported on the specified property path 'ID'"