Scripting: "get -delete" doesn't work

I'm using a script to download files and delete them after download.

using the commands

get *.txt myfolder
rm *.txt

works, but if files are uploaded in between these commands, they are being deleted without having been downloaded.

So I tried

get -delete *.txt myfolder

which results in this:

2008-07-02 17:47:05.654 Listing file "-delete".
> 2008-07-02 17:47:05.654 Type: SSH_FXP_LSTAT, Size: 21, Number: 263
< 2008-07-02 17:47:05.732 Type: SSH_FXP_STATUS, Size: 31, Number: 263
< 2008-07-02 17:47:05.732 Status/error code: 2, Message: 263, Server: No such file, Language: en
. 2008-07-02 17:47:05.748 Closing connection.

Where's my mistake? Thanks for a clue

All scripting switches (including -delete) are supported since 4.1.x only.

Thanks Martin, for your help and for WinSCP in general!!!