Error from Interface Tools

[Stavi]

Hey all,

I built an application that opens new columns

     and allows the user to choose which column from the source input file to enter into the new columns.

When the user does not choose any column, the default is a V_Wstring column, name: [test]

All the Formula tools, Text Box tools and Action tools are configured the same way, allowing "[None]" choice. in some cases when the user does not choose a column the default [test] remains, but for others the result is totally empty and I get an error:

Can you think of a reason for the different reactions between same-configured action tools?

[apathetichell]

can you show us the action tool configuration for the third formula?

[Stavi]

[apathetichell]

try reconfiguring it to "update value with formula"

then use the formula toString([#1])