I know this is probably not relevant for you anymore, but maybe somebody will search it in the future like I did.
I had a similar problem like you. My command was:
spectrast -cN<outputfilename> -cP<minProb> -co! <File1> [ <File2> … <FileN> ]
as stated when using the spectrast -c command and reading the help.
However this doesnt work and I got the same error message as you, because spectraST recognised the "[" and "]" as librarys with different extensions.
So in my case the solution was simply to remove the brackets.
spectrast -cN<outputfilename> -cP<minProb> -co! <File1> <File2> … <FileN>
Maybe in your case its something similar, like removing "<" and ">".