Sprite error on Act Editor

[Loki Mania]

Hello, i am trying to edite some sprites, i replace .bmp with Act Editor, save it, but when i try to open, it shows this error:

Quote

Offset and length were out of bounds for the array or count is greater than the number of elements from index to the end of the source collection.

Full exception:

--------------          Message          --------------
Offset and length were out of bounds for the array or count is greater than the number of elements from index to the end of the source collection.
--------------        Stack trace        --------------
   em GrfToWpfBridge.Application.DefaultErrorHandler._reportAnyManagedExceptions(String message, Exception exception, ErrorLevel errorLevel)
   em GrfToWpfBridge.Application.DefaultErrorHandler.Handle(Exception exception, ErrorLevel errorLevel)
   em ActEditor.Core.ActEditorWindow._openFromFile(String file)
   em ActEditor.Core.ActEditorWindow._open(TkPath file)
   em ActEditor.Core.ActEditorWindow._miOpen_Click(Object sender, RoutedEventArgs e)
   em System.Windows.RoutedEventHandlerInfo.InvokeHandler(Object target, RoutedEventArgs routedEventArgs)
   em System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised)
   em System.Windows.UIElement.RaiseEventImpl(DependencyObject sender, RoutedEventArgs args)
   em System.Windows.UIElement.RaiseEvent(RoutedEventArgs e)
   em System.Windows.Controls.MenuItem.InvokeClickAfterRender(Object arg)
   em System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)
   em System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Int32 numArgs, Delegate catchHandler)
   em System.Windows.Threading.DispatcherOperation.InvokeImpl()
   em System.Windows.Threading.DispatcherOperation.InvokeInSecurityContext(Object state)
   em System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   em System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   em System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
   em MS.Internal.CulturePreservingExecutionContext.Run(CulturePreservingExecutionContext executionContext, ContextCallback callback, Object state)
   em System.Windows.Threading.DispatcherOperation.Invoke()
   em System.Windows.Threading.Dispatcher.ProcessQueue()
   em System.Windows.Threading.Dispatcher.WndProcHook(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
   em MS.Win32.HwndWrapper.WndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
   em MS.Win32.HwndSubclass.DispatcherCallbackOperation(Object o)
   em System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)
   em System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Int32 numArgs, Delegate catchHandler)
   em System.Windows.Threading.Dispatcher.LegacyInvokeImpl(DispatcherPriority priority, TimeSpan timeout, Delegate method, Object args, Int32 numArgs)
   em MS.Win32.HwndSubclass.SubclassWndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam)
   em MS.Win32.UnsafeNativeMethods.DispatchMessage(MSG& msg)
   em System.Windows.Threading.Dispatcher.PushFrameImpl(DispatcherFrame frame)
   em System.Windows.Threading.Dispatcher.PushFrame(DispatcherFrame frame)
   em System.Windows.Application.RunDispatcher(Object ignore)
   em System.Windows.Application.RunInternal(Window window)
   em System.Windows.Application.Run(Window window)
   em ActEditor.GRFEditorMain.Main(String[] args)

--------------         Exception         --------------
System.ArgumentException: Offset and length were out of bounds for the array or count is greater than the number of elements from index to the end of the source collection.
   em System.Buffer.BlockCopy(Array src, Int32 srcOffset, Array dst, Int32 dstOffset, Int32 count)
   em GRF.IO.ByteReader.Bytes(Int32 count)
   em GRF.FileFormats.SprFormat.SprAbstract._readAsBgra32(List`1 rleImages, IBinaryReader reader)
   em GRF.FileFormats.SprFormat.SprAbstract._getImages(Spr spr, IBinaryReader reader, Boolean loadFirstImageOnly)
   em GRF.FileFormats.SprFormat.SprAbstract.GetImages(Spr spr, IBinaryReader reader, Boolean loadFirstImageOnly)
   em GRF.FileFormats.SprFormat.Spr..ctor(Byte[] dataDecompressed, Boolean loadFirstImageOnly)
   em ActEditor.Core.ActEditorWindow._openFromFile(String file)