Finaly I found the problem:
1. There was nothing wrong with my lisp-code
2. Theo was nothing wrong with my DCL-file
For some odd reason the projectfile was the problem. The DCL-file was not merged while compiling the source.
The require-file-list line was wrong (see below), The correct line must be: (:require-file-list (:DCL "Proef.DCL"))
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;;; Visual LISP make file [V1.0] PROEF saved to:[D:/Theo/extra/acad-extra] at:[3/1/21]
(PRV-DEF (:target . "PROEF.VLX")
(:active-x . T)
(:separate-namespace)
(:protected . T)
(:load-file-list (:lsp "Proef.LSP"))
(:require-file-list (:lsp "Proef.DCL"))
(:ob-directory)
(:tmp-directory)
(:optimization . st)
)
;; EOF
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