Hello for all!

I have a question about tegprefix technology in WinCC RT Prof V14.1. I created subscreen with his tagprefix (according to example TagPrefix example TIA v14). But now i need to save in the file csv all tags from my subscreen in depend of the current tag prefix.

For example:

I made the struct 'FAN"  that contains tags: "SetTemp, SetSpeed ". On subscreen i have Iofields connected to "  .SetTemp" and "  .SetSpeed" respectively .  I  have several FANS.  Now, when i open this subscreen in my main screen i can see value in IoFields depend of "tagprefix" .SetTemp and "tagprefix" .SetTSpeed. But  i need to write or read  in / from  file the current value of the connected tag.

I made buttons on subscreen with vb scripts for read/write data in /from file:

Is it right syntax for this task? This code dosn't work

For write in file