Receiving 405 web method not allowed when posting data back

Looking at the help page for the Dynamic Modules Data.svc tells me if I want to create a data item I need to use this uri:

/Sitefinity/Services/DynamicModules/Data.svc//dataItemId/?provider=provider&itemType=itemType&workflowOperation=workflowOperation

I specify the uri like this:

/Sitefinity/Services/DynamicModules/Data.svc//?provider=&workflowOperation=Publish&itemType=Telerik.Sitefinity.DynamicTypes.Model.Notifications.Notification

To create a data item you need to specify a PUT and I'm doing that. Last the data format I send back looks like this:

"Item":

    "ExternalControl":true,

"Id":null,

"Lifecycle":null,

"Message":"PersistedValue":null,"Value":"The website is unexpectedly down right now. Sorry for the inconvenience. We will be back up shortly.",

"Title":"PersistedValue":null,"Value":"Website is down"

I'm creating a new Notification so I can't possibly specify all the information that you would send in your PUT call and "web method not allowed" doesn't tell me if there's something wrong with my format. I am succeeding in authenticating or else my get data calls wouldn't be working and I'd be receiving an entirely different error so I know authenticating is not the problem. So what am I doing wrong when the uri, request type, and the data format is correct?