c# - FindByIdentity failing with PricipalOperationException in ASP.NET webapp

I'm struggling with an issue in utilizing System.DirectoryServices.AccountManagement in my internal web application. The error is not very descriptive, but here's what's going on:

When I attempt to validate that a provided user id exists in the AD, I do so with the following code:

private bool IsWindowsIDValid(string strWindowsID) 
{ 
var context = new PrincipalContext(ContextType.Domain, "DOMAINSERVER", "DC=DOMAINNAME,DC=net"); 
var userPrincipal = UserPrincipal.FindByIdentity(context, strWindowsID); 
return (userPrincipal != null); 
} 

However, an exception is throw at the second line, where FindByIdentity is called. Here are the exception details:

Message:
"An operations error occurred."

Stack trace:

at System.DirectoryServices.AccountManagement.PrincipalContext.DoLDAPDirectoryInit()
at System.DirectoryServices.AccountManagement.PrincipalContext.DoDomainInit()
at System.DirectoryServices.AccountManagement.PrincipalContext.Initialize()
at System.DirectoryServices.AccountManagement.PrincipalContext.get_QueryCtx()
at System.DirectoryServices.AccountManagement.Principal.FindByIdentityWithTypeHelper(PrincipalContext context, Type principalType, Nullable`1 identityType, String identityValue, DateTime refDate)
at System.DirectoryServices.AccountManagement.Principal.FindByIdentityWithType(PrincipalContext context, Type principalType, String identityValue)
at System.DirectoryServices.AccountManagement.UserPrincipal.FindByIdentity(PrincipalContext context, String identityValue)
at *****.IsWindowsIDValid(String strWindowsID) in *****.ascx.cs:line 193

This same error occurs if I attempt to examine the ConnectedServer property of the PrincipalContext as well. However, I can attempt to validate credentials against the context (using context.ValidateCredentials()), and it will pass just fine.

Any ideas as to what may be going on? I can run this code just fine in a stand alone console script on my machine - this is occurring in my local development environment, inside VisualStudio, when I attempt to debug the webapp. Is this a permissions issue or something else perhaps? I'm pretty lost at this point.

I appreciate any help!

-Patrick