do you have 64Bit Libs ?
because on 64Bit Win you will need the 64 Bit Libs (e.g x64 directories of bass;bass_vst ZipFiles)
by the way you can try this to check if the error comes from bass or Bass_Vst
if BASS_Init(0, 44100, 0,0, nil) then
begin
ch := BASS_StreamCreate(44100, 2,BASS_SAMPLE_FLOAT, nil, nil);
if ch <> 0 then
begin
dsp := BASS_VST_ChannelSetDSP(ch, PChar(FileName), BASS_UNICODE, 0);
if dsp = 0 then
ShowMessage(' VST-Error Nr ,'+Bass_ErrorGetCode().tostring);
if ch <> 0 then
BASS_StreamFree(ch);
end
else
ShowMessage(' Bass-Error Nr ,'+Bass_ErrorGetCode().tostring);
end;