Intellisense (go to Definition) not working

[tpenrod]

I am running Visual Studio, C#.

Intellisense "Go to Definition" function has stopped working for most
objects It appears to work for some class variables, but not for other
methods or variables.
E.g. in the example below, if I go to the reference to planXML, rclick and
select "Go to Definition" I get a popup box saying "Cannot Navigate to
planXML", even though it's defined two lines above.

[WebMethod()]
public DataSet ReadPlan(string jobNumber, string entpId, string jecCode)
{
try
{
string planXml =
ConfigurationSettings.AppSettings["planByJobNumberXml"];
StringBuilder sb = new StringBuilder();
sb.AppendFormat(planXml, jobNumber, entpId, jecCode);