Hi Gavin,
Does your point layer display correctly in snapshot mode? What about as a Dynamic layer?
Could there be a scale dependency which is preventing the points from showing? Look for the Min. Scale: and Max. Scale: values in the REST services directory (eg here)
Steve
Do you see any messages in the Firefox or Chrome JavaScript console when you load the layer? Does this layer have a visible ObjectID field? Specifically, do you see an ObjectID field when you look at the layer via the services directory?
Any chance you can provide a link to your services directory and/or your app?
Yes, your feature layer needs an OID field. Do you see a message about this in the firebug or chrome dev tools console?
What is the format for the underlying data?