diff --git a/Credential.cs b/Credential.cs
index d089b72..6d6a443 100644
--- a/Credential.cs
+++ b/Credential.cs
@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.DirectoryServices.AccountManagement;
 using System.Linq;
 using System.Text;
 using System.Threading.Tasks;
@@ -16,6 +17,8 @@ namespace NSspi
         {
             this.disposed = false;
 
+            this.securityPackage = package;
+            
             Init();
         }
 
diff --git a/CredentialUse.cs b/CredentialUse.cs
new file mode 100644
index 0000000..65623b1
--- /dev/null
+++ b/CredentialUse.cs
@@ -0,0 +1,15 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace NSspi
+{
+    public enum CredentialUse : int
+    {
+        Inbound = 1,
+        Outbound = 2,
+        Both = 3,
+    }
+}
diff --git a/NSspi.csproj b/NSspi.csproj
index 8a4d938..62b739e 100644
--- a/NSspi.csproj
+++ b/NSspi.csproj
@@ -32,6 +32,8 @@
   <ItemGroup>
     <Reference Include="System" />
     <Reference Include="System.Core" />
+    <Reference Include="System.DirectoryServices" />
+    <Reference Include="System.DirectoryServices.AccountManagement" />
     <Reference Include="System.Xml.Linq" />
     <Reference Include="System.Data.DataSetExtensions" />
     <Reference Include="Microsoft.CSharp" />
@@ -39,8 +41,14 @@
     <Reference Include="System.Xml" />
   </ItemGroup>
   <ItemGroup>
-    <Compile Include="Class1.cs" />
+    <Compile Include="Credential.cs" />
+    <Compile Include="CredentialPackage.cs" />
+    <Compile Include="CredentialType.cs" />
+    <Compile Include="CredentialUse.cs" />
+    <Compile Include="NativeMethods.cs" />
+    <Compile Include="PackageNames.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
+    <Compile Include="SSPIException.cs" />
   </ItemGroup>
   <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
   <!-- To modify your build process, add your task inside one of the targets below and uncomment it. 
diff --git a/NativeMethods.cs b/NativeMethods.cs
index 8678072..33275fe 100644
--- a/NativeMethods.cs
+++ b/NativeMethods.cs
@@ -9,6 +9,9 @@ namespace NSspi
 {
     public class NativeMethods
     {
+
+        // http://msdn.microsoft.com/en-us/library/windows/desktop/aa374713(v=vs.85).aspx
+
         /*
         SECURITY_STATUS sResult = AcquireCredentialsHandle(
 		        NULL,											// [in] name of principal. NULL = principal of current security context
@@ -35,17 +38,17 @@ namespace NSspi
             );
         */
 
-        [DllImport( "Secur32.dll", CallingConvention = CallingConvention.Winapi, SetLastError=false)]
+        [DllImport( "Secur32.dll", CallingConvention = CallingConvention.Winapi, SetLastError=true)]
         public extern int AcquireCredentialHandle(
             string principleName,
             string packageName,
-            int credentialUse,
+            CredentialUse credentialUse,
             IntPtr loginId,
             IntPtr packageData,
             IntPtr getKeyFunc,
             IntPtr getKeyData,
             IntPtr credentialHandle,
-            long expiry
+            ref long expiry
         );
     }
 }