Windows 7 - Time line problem in Windows Media Player

Hello every body
I use this code to add logo on my movie ( by use Coding on avisynth soft and run code on meGUI soft )

LoadPlugin("C:\Program Files\AviSynth 2.5\plugins\RemapFrames\RemapFrames.dll")
FPS=23.976
a1=DirectShowSource("Movie.mkv",fps=FPS)
a1=AssumeFPS(a1, FPS)
a2=ImageSource("logo(1280x688).png",pixel_type="RGB32")
a3=Overlay(a1,a2,mask=a2.ShowAlpha())
ReplaceFramesSimple(a1, a3, mappings="[1105 3000][121092 121332][231184 231424]")
LanczosResize(1280,688)

When i use this code, the voice has been seperate from the movie!
And when i play the movie without a voice there is not a problem and file play correctly with Windows Media Player!
when i add voice to movie with mkv muxer tools in MeGui software ,and i play the converted movie on Windows Media Player , the time line does not work Correct ( see the follow picture )

http://8208.6.img98.net/out.php/i191228_1.jpg

Although the time line is in the Middle of page , but the movie is finished !!!
this problem is only in Windows Media Player and other software for example JetAudio or Kmplayer does not have this problem
plz help me to solve this problems


If you know better code to add logo on movie ( like my code ) and have better speed for convert please Show me
I realy need this

Thank you very much