I'm trying to run muscle using the Bioconductor package. I get an error that yields almost no hits on google. The error is clearly in the 

out="test.aln"

because when I delete this parameter the script works as intended. Maybe someone can point me in the right direction? 

Thanks in advance,

Dave

# Test script for muscle
source("https://bioconductor.org/biocLite.R")
biocLite()
library(XVector)
library(Biostrings)
biocLite("muscle")
library(muscle)

alignment <- muscle(umax, out="test.aln", quiet = FALSE)

>Error in .Call2("new_input_filexp", filepath, PACKAGE = "XVector") :
  cannot open file '/var/folders/lr/67cs0zdh8vl_cn0059_vv2vr0000gr/T//RtmpP0C0KJ/file6d03ecc6ce6.afa'

sessioninfo()

R version 3.4.0 (2017-04-21)
Platform: x86_64-apple-darwin15.6.0 (64-bit)
Running under: macOS Sierra 10.12.3

Matrix products: default
BLAS: /System/Library/Frameworks/Accelerate.framework/Versions/A/Frameworks/vecLib.framework/Versions/A/libBLAS.dylib
LAPACK: /Library/Frameworks/R.framework/Versions/3.4/Resources/lib/libRlapack.dylib

locale:
[1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8

attached base packages:
[1] stats4    parallel  stats     graphics  grDevices utils     datasets 
[8] methods   base     

other attached packages:
[1] muscle_3.18.0        Biostrings_2.44.0    XVector_0.16.0      
[4] IRanges_2.10.1       S4Vectors_0.14.1     BiocGenerics_0.22.0 
[7] BiocInstaller_1.26.0

loaded via a namespace (and not attached):
[1] zlibbioc_1.22.0 compiler_3.4.0  tools_3.4.0    
>