not able to encode under Vista 64

[onix]

Hi there,
I'm trying to use the 64 bit version of x264 (CLI) available at http://members.optusnet.com.au/squid_80 but I get the message: "can't open input file"
Software:
Avisynth 2.57
DGdecode 1.4.8
x264 32 bit 616 (no problem)
x264 64 bit 03-01-2007
Vista x64 RC2
I've tried to change both Avisynth and DGdecode to their 64 bit counterparts (along with Avisynth 2.55 and DG 1.4.6), and yet I get the same erro

[DeeGee]

Well what kind of input file do you have? Do you have the 64-bit filters to input the file?

[onix]

It's an avs file.
The only filter woul be bicubic resizing, but that one's internal right?
As for plug-ins, DGdecode (64 bit).