How To Display Error Messages

I've got an app I'm working on that sometimes will give me an error message and sometimes it won't. When it doesn't it just displays "Page cannot be displayed". Is there a code that will allow asp to display the error messages?

Here's the code I was using:

<%
dim objComm
set objComm = Server.createObject ("adodb.command")
objComm.activeconnection = MM_dbConn_STRING
objcomm.commandText = "dbo.aIssue"
objComm.commandtype = "adCmdStoredProc"
objComm.execute
%>