no doc in modules

Version: 21.2.38 Platform: SCO 5.0.2, gcc 2.95.2 M-x load-module sample (sample-function) works, but (documentation 'sample-function) returns nil. C-h f sample-function Signaling: (wrong-type-argument stringp nil) string-match("[\n ]*\narguments: ?(\\(.*\\))\n?\\'" nil) function-arglist(sample-function) describe-function-1(sample-function) #<compiled-function nil "...(10)" [describe-function-1 function buffer-string nil standard-output] 4>() with-displaying-help-buffer(#<compiled-function nil "...(10)" [describe-function-1 function buffer-string nil standard-output] 4> "function `sample-function'") #<compiled-function (function) "...(8)" [with-displaying-help-buffer #<compiled-function nil "...(10)" ... 4> format "function `%s'" function] 5 868529 (let* (... ...) (list ...))>(sample-function) call-interactively(describe-function)