confint.merMod(method="boot") {lme4} with user supplied FUN to bootMer fails

Dear list,

I'm trying to supply a summary function to confint.merMod(method="boot")
 {lme4} but get persistent
errors. The following example generates the errors:

fm1 <- lmer(Reaction ~ Days + (Days | Subject), sleepstudy)
test = function(fit) fixef(fit)[1]
test(fm1)

(Intercept) 
   251.4051 

confint(fm1, method="boot", FUN=test)

Computing bootstrap confidence intervals ...
Error in set.seed(seed) : supplied seed is not a valid integer

confint(fm1, method="boot", FUN=test, seed=100)

Computing bootstrap confidence intervals ...
Error in if (use.u) NULL else ~0 : 
  argument is not interpretable as logical

confint(fm1, method="boot", FUN=test, seed=100, use.u = FALSE)

Computing bootstrap confidence intervals ...
Error in match.arg(type) : 'arg' must be NULL or a character vector

confint(fm1, method="boot", FUN=test, seed=100, use.u = TRUE)

Computing bootstrap confidence intervals ...
Error in match.arg(type) : 'arg' must be NULL or a character vector

Any help/hints/ideas?

Cheers,

Torbj?rn