Layers are getting displayed in TOC but Map control is blank

Usually when you install the ArcGIS Server .Net web adf , it will add some entries in http handler section of web.config at machine level i.e c:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\CONFIG\web.config.

But sometimes it will not add these entries. Basically your map control in .Net application use these web handlers to get tiles on request (pan,zoom etc). when it cant find these entries in the web.config then it throws error on retrieving tiles which is the reason why your map is blank although everything else seems working.

So when you get a blank map control with layers showing up on TOC , one of the reasons could be these missing entries. so just copy the below code if you dont have a httpHandlers section in web.config of your application or add the entries into your http handler section of web.config if you have one.

Note: The above entries refer to the arcgis server WebADF sp3 version. you have to change the version and PublicKeyToken If you are using a different version of Web ADF.