impacts in spdep does not work for me when there is only one predictor

Dear Roger and others,

Using the impacts function in spdep to calculate distributions (on the 
regression parameters from the spatial lag model) I encountered the following 
problem: when there is only one exogenous predictor in the model the impacts 
function won't give the output summary of the mcmc simulations. Given the 
time the function takes to produce the error I think that the simulations do 
run.

I tried the same on the columbus data where it also happens

example(columbus)
listw <- nb2listw(col.gal.nb)
lobj  <- lagsarlm(CRIME ~ INC, columbus, listw)
summary(lobj)
imp   <- impacts(lobj, listw=birds.wlist, R=100)
summary(imp,  zstats=TRUE)

Error in dimnames(x) <- dn :
 length of 'dimnames' [2] not equal to array extent

lobj  <- lagsarlm(CRIME ~ INC + HOVAL, columbus, listw)
summary(lobj)
imp   <- impacts(lobj, listw=birds.wlist, R=100)
summary(imp,  zstats=TRUE)

works fine.

I hope I didn't miss anything obvious.
Thanks in advance,
Eelke