Getting Exception while using Drools 3.0

I am trying to implement Drools in .Net. I am new to .Net as well as Drools.I've read the following document for implementation of Drools:

http://www.codeproject.com/Articles/29165/Getting-Started-with-Drools-NET

I've downloaded this project and it was working fine. Here is my code which I have implemented:-

requirementBusinessRules = this;
            PackageBuilder builder = new PackageBuilder();
            Stream stream = new FileStream(@"C:\Users\Sdixit\Desktop\LatesetVersion\ReadMails\SimpleRulesExt.drl", FileMode.Open);           
            builder.AddPackageFromDrl("SimpleRules.drl", stream);   // Exception
            Package pkg = builder.GetPackage();
            ruleBase = RuleBaseFactory.NewRuleBase();
            ruleBase.AddPackage(pkg);           
            workingMemory = ruleBase.NewWorkingMemory();           
            if (_currentRawMail == null)            {
                _currentRawMail = requirementBusinessRules.workingMemory.assertObject(em); 
            }
            else
            {
                requirementBusinessRules.workingMemory.modifyObject(_currentRawMail, em);
            }
            requirementBusinessRules.workingMemory.fireAllRules();
            EmailProperties mails = (EmailProperties)requirementBusinessRules.workingMemory.getObject(_currentRawMail);

drools.dotnet.dll!org.drools.dotnet.semantics.DotnetBaseClassFieldExtractor.DotnetBaseClassFieldExtractor(java.lang.Class clazz, string fieldName) Line 61 + 0x13 bytes C#
drools.dotnet.dll!org.drools.dotnet.semantics.DotnetClassFieldExtractorFactory.getClassFieldExtractor(java.lang.Class clazz, string fieldName) Line 50 + 0x1b bytes C#
[External Code] 
drools-3.0.dll!org.drools.base.ClassFieldExtractor.init() Line 73 + 0x58 bytes  Unknown
drools-3.0.dll!org.drools.base.ClassFieldExtractor.ClassFieldExtractor(java.lang.Class clazz, string fieldName) Line 53 Unknown
drools-3.0.dll!org.drools.base.ClassFieldExtractorCache.getExtractor(java.lang.Class clazz, string fieldName) Line 27 + 0x1d bytes  Unknown
drools-3.0.dll!org.drools.semantics.java.RuleBuilder.getFieldExtractor(org.drools.lang.descr.PatternDescr descr, java.lang.Class clazz, string fieldName) Line 998 + 0x1b bytes Unknown
drools-3.0.dll!org.drools.semantics.java.RuleBuilder.build(org.drools.rule.Column column, org.drools.lang.descr.LiteralDescr literalDescr) Line 527 + 0x36 bytes    Unknown
drools-3.0.dll!org.drools.semantics.java.RuleBuilder.build(org.drools.lang.descr.ColumnDescr columnDescr) Line 431 + 0x36 bytes Unknown
drools-3.0.dll!org.drools.semantics.java.RuleBuilder.build(org.drools.lang.descr.RuleDescr ruleDescr) Line 303 + 0x3e bytes Unknown
drools-3.0.dll!org.drools.semantics.java.RuleBuilder.build(org.drools.rule.Package pkg, org.drools.lang.descr.RuleDescr ruleDescr) Line 203 Unknown
drools-3.0.dll!org.drools.compiler.PackageBuilder.addRule(org.drools.lang.descr.RuleDescr ruleDescr) Line 337 + 0x1b bytes  Unknown
drools-3.0.dll!org.drools.compiler.PackageBuilder.addPackage(org.drools.lang.descr.PackageDescr packageDescr) Line 204 + 0x4a bytes Unknown
drools-3.0.dll!org.drools.compiler.PackageBuilder.addPackageFromDrl(string fileName, java.io.Reader reader) Line 129    Unknown
drools.dotnet.dll!org.drools.dotnet.compiler.PackageBuilder.AddPackageFromDrl(string fileName, System.IO.Stream drlStream) Line 78 + 0x2b bytes C#

But I am getting an Exception "NullReferenceException unhandled by user code .object reference not set to an instance of an object." What to do Now?? What am I missing here?? I went through Drools: NullPointerException when addPackageFromDrl(source) is called

I am using Drools 3.0 and Visual Studio 2012 Thanks
I have found that Drools 6 is the latest version but when i installed it in my pc i found that it contains only .jar file no .dll files . Thanks Please Help!

Tags: C#, Visual Studio