Creating objects in the REST API

Hi everyone. 

I'm having some trouble with the REST API. I'm getting an error I can't seem to figure out.
When I try to create an object, no matter what exactly the type or class is, I get an 500 error with code 154 in the text and also: 'Wrong data type for property definition "Name".'

My input payload is as follows:

{"PropertyValues":
           [{"PropertyDef": 0, "TypedValue": { "DataType": 1, "Value": 'test'}}
           ,
            {"PropertyDef ":  100,"TypedValue":{"DataType":9,"Lookup":{"Item":0,"Version":-1}}}]}
As far as I can see the DataType : 1 is correct for Property 0, which is the built-in property Name.
Does anyone know what this might cause this?