You can't put the name of a variable after the CALL keyword. CALL doesn't allow that. CALL regards any name as a literal string, even if it isn't quoted.
To allow variable substitution. Reginald allows you to use brackets to indicate the same, ie:myvariable = "blort"
CALL [myvariable] But this doesn't work for other interpreters, so you'd have to resort to the slower:INTERPRET "CALL" myvariable Incidentally, if you know the full path to the script beforehand, you can hardcode it right in your call instruction, but do quote it as so:"C:\MyDir\MySubDir\child.rex"() |