Multiple WCF services referencing the same data contracts

Question

I am building a set of WCF services that share common data contracts (or entities if you prefer). These are simple data transfer objects that are decorated with DataContract

Answer 1

I also tend to keep all my Data Contracts in one assembly which is referenced by multiple services and numerous client apps, which works great but I've never tried consuming the service outside of .NET.

It might be helpful to know what technology they are using to consume the service other than .NET? What is throwing the ambigious reference message?