If one is using more than one string argument it seems like csound get confused
Here is an example
p4 is a name for a wavefile
p5 is a name for a convolution analysis file
it looks like csound only can take one string argument and then uses the last one
it tries to read the convolvefile as a wavefile and then complains that it haven't got a header

;orc
sr=44100
kr=4410
ksmps=10
nchnls=2

instr 1
 al,ar diskin p4,0.25
 aoutl,aoutr convolve al,p5
 outs aoutl,aoutr
endin

;sco
i1 0 10 "vannspeeddown2.WAV" "vannspeeddown1.cvanal"

;output :

MIT Csound: 3.53 (Mar 21 1999)
orch now loaded
graphics not supported on this terminal, ascii substituted
audio buffered in 16384 sample-frame blocks
writing 65536-byte blks of shorts to D:\WINNT\Profiles\roger\Desktop\convolve_test.WAV (WAV)
SECTION 1:
new alloc for instr 1:
WARNING: no soundin header, presuming orchestra sr
WARNING: E:\VirginMother/vannspeeddown1.cvanal has no soundfile header, reading
as shorts, 2 chnls
audio sr = 44100, stereo, reading channel 2
file E:\VirginMother/vannspeeddown1.cvanal (67108920 bytes) loaded into memory
..........................
B  0.000 .. 10.000 T 10.000 TT 10.000 M:      0.0
 0.0
end of score.              overall amps:      0.0      0.0
           overall samples out of range:        0        0
0 errors in performance
.27 65536-byte soundblks of shorts written to D:\WINNT\Profiles\roger\Desktop\co
nvolve_test.WAV (WAV)