Although ArcGIS Server is not required to host a CSV file web service you may experience the similar hosting issues of accessing the web service as described in the ArcGIS Resource Center blog entitled Troubleshooting blank layers. Specifically, you may need to make sure that a correct cilentaccesspolicy.xml or crossdomain.xml file is in place on the web servers root. If a clientaccesspolicy.xml or crossdomainpolicy.xml file cannot be used on your web server for situations like secure services you may need to use a proxy page on your web server and make use of the ProxyUrl Property.