New Post: _rasterizer.Open(ms) throws System.NullReferenceException in .net 4.5

Hi, my code looks like this:

MemoryStream ms = new MemoryStream(bytes);
if (_rasterizer != null)
{
   _rasterizer.Dispose();
}
_rasterizer = new GhostscriptRasterizer();
_rasterizer.Open(ms);

Pretty much like the sample code
The error happens at _rasterizer.Open(ms).
This happens only when I'm using .net 4.5.
Both ghostscript and windows is x64.

The whole error :

System.NullReferenceException was unhandled by user code
  HResult=-2147467261
  Message=Object reference not set to an instance of an object.
  Source=Ghostscript.NET
  StackTrace:
       at Ghostscript.NET.Interpreter.GhostscriptInterpreter.InitArgs(String[] args)
       at Ghostscript.NET.Viewer.GhostscriptViewer.Open()
       at Ghostscript.NET.Viewer.GhostscriptViewer.Open(String path, GhostscriptVersionInfo versionInfo, Boolean dllFromMemory)
       at Ghostscript.NET.Viewer.GhostscriptViewer.Open(Stream stream, GhostscriptVersionInfo versionInfo, Boolean dllFromMemory)
       at Ghostscript.NET.Rasterizer.GhostscriptRasterizer.Open(MemoryStream stream, GhostscriptVersionInfo versionInfo, Boolean dllFromMemory)
       at LightSwitchApplication.ApplicationDataService.BøgerSet_Updated(Bøger entity)
       at LightSwitchApplication.ApplicationDataService.DetailsClass.__BøgerSet_Updated(ApplicationDataService d, Bøger e)
       at Microsoft.LightSwitch.Details.Framework.Server.EntitySetEntry`2.Microsoft.LightSwitch.Details.Framework.Server.IEntitySetEntry.InvokeUpdated(IDataService dataService, IEntityObject entity)
       at Microsoft.LightSwitch.ServerGenerated.Implementation.DataServiceImplementation`1.<>c__DisplayClass61.<PerformPostEvent>b__5c(IEntitySetEntry entitySetEntry)
       at Microsoft.LightSwitch.ServerGenerated.Implementation.DataServiceImplementation`1.<>c__DisplayClass43.<CallPrePostUserCode>b__42()
       at Microsoft.LightSwitch.Utilities.Internal.UserCodeHelper.CallUserCode(Type sourceType, String methodName, String instance, String operation, ILoggingContext context, Action action, String additionalText, Func`1 getCompletedMessage, Boolean tryHandleException, Boolean swallowException, Exception& exception)
  InnerException: