Creating a Buid via REST API

We are trying to create a build via the REST API of Spira but we are not succeeding.

We post to url: /Services/v5_0/RestService.svc/projects/1/releases/175/builds

However whatever we pass in the body we receive the following error (full trace at the bottom):

'The associated release/iteration RL0 does not exist in the current project'

It seems like he does not read the release id correctly.
Could you have a look and let me know if this could be a bug or advice on what could be going wrong

<p>The server encountered an error processing the request. The exception message is 'The associated release/iteration RL0 does not exist in the current project'. See server logs for more details. The exception stack trace is: </p>
            <p>   at Inflectra.SpiraTest.Business.BuildManager.Insert(Int32 projectId, Int32 releaseId, String name, String description, DateTime creationDate, BuildStatusEnum status, Int32 userId)
   at Inflectra.SpiraTest.Web.Services.v5_0.RestService.Build_Create(String project_id, String release_id, RemoteBuild remoteBuild)
   at SyncInvokeBuild_Create(Object , Object[] , Object[] )
   at System.ServiceModel.Dispatcher.SyncMethodInvoker.Invoke(Object instance, Object[] inputs, Object[]&amp; outputs)
   at System.ServiceModel.Dispatcher.DispatchOperationRuntime.InvokeBegin(MessageRpc&amp; rpc)
   at System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage5(MessageRpc&amp; rpc)
   at System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage11(MessageRpc&amp; rpc)
   at System.ServiceModel.Dispatcher.MessageRpc.Process(Boolean isOperationContextSet)</p>