Avisynth - FOURCC code not found

[mrmrmrmr]

Hi,

I am using the "Stereo Movie Maker" software with Avisynth. It's very useful for people like me who has Fujifilm 3d cameras.
To open/import files except MPEG1/2 this software requires Avisynth to be installed.

I am trying to open an MP4 file with AVC video in it.
I have Avisynth installed on my PC (I use a Windows 7 computer with K-Lite codec pack installed)
Stereo Movie Maker says:
"Not available AVI File" , "Your videodoes not have FOURCC code"

The video has "avc1" as FOURCC code and it can be played with default Windows Media Player.

I tried same operation on a Windows XP computer and it is successful.
It also has Avisynth installed and K-Lite Codec Pack. But an older version of the codec pack.
I don't know what is the difference that disables me from opening same movie on my Windows 7 computer.
Do you have any ideas ?

Thanks,
ilker