Need help flv in virtualdub

Currently I am using virtualdubmod 1.5.10.2, I used flvextract to demerge a flv file into an avi and mp3, I try to load the avi in to virtualdub and I get an error message as :-

Couldn't locate decompressor for format 'FLV1' (unknown).
VirtualDub requires a Video for Windows (VFW) compatible codec to
decompress video.

But I have ffdshow installed and enabled for flv1 and the avi plays fine in wmp11, can you tell me whats the issue out ?

Instead of using an outdated and discontinued fork, why not use latest VirtualDub with FLV input plugin.
In this way you don't need to demerge the FLV file and you will get all the VirtualDub improvements/fixes also.

Thanks i will do it