Is this a bug? "Wrong type argument: wholenump"

[Fr Ml]

Hello, I'm trying to extract some information from cells in tables. I get this problem. | text        | splitted | |-------------+----------| | part1 part2 | #ERROR   | #+TBLFM: $2='(split-string $1) As you see, I  get an ERROR,. I expect: "part1" "part2". The debugger says: org-table-eval-formula: Wrong type argument: wholenump, "part1". Is this a bug? Or did I misunderstand the syntax? (Emacs-version: 27.1, Org-version: 9.4.4, I tried also "emacs -Q". Same problem.) Kind Regards Frank