Jonathan,
The command line you want to use is:
freq +u +t*CHI +sm|n,|n:*,~|poss filename.cha
The reason you got the error message is because your file "13FKMRMC.CHA" does not have speaker "*CHI". The other problem is that in CHAT English grammar possessive parts of speech are marker as "~poss", so I don't understand why you were looking for past tense words. The command you have in your attached PDF file would locate all noun words and all past tense words, if the *CHI speaker was present in that file. One more comment I would like to make is that ",**" at the end of +r4 option will be ignored by CLAN, because it make no sense there.