[Therion] join command

Hello, in one case the "join" command doesn`t works on my computer. Version Therion 5.2.7 I have two scraps in one *.th2-file. There are only two lines (type wall) in that second scrap. So I have, like described in TB, given IDs to that two lines and to two other lines in the first scrap. Then I have written this command line in my *.th-file after "endcenterline"-command. join VH10_L1@VH10:0 VH10_L3@VH10:0 It gives a "survey does not exist -- VH10" error. If I comment out the line it works without a problem. The map is written but the lines resp. the points of the lines are not connected. And that was it, what I wanted to do. Where is the fault, which I make? regards Markus