Couldn't extract another token

[hexfur]

So I’m adding an input_text choice to choose the first part of your name.
Here’s my startup file:

*create na "---"
*create na1 "---"
*create na2 "second_name"

na = Name
na1 = (inputted name)
na2 = (preset secondary name)

The secondary name changes up to two times, with a possible third time
The input code is below, and that working (below)

#let me pick!
  *input_text na1
  *set na $!{na1}${na2}

But later on in the game the secondary name gets changed

*if (name = "preset name)
  *set name "preset second name"
  *finish
*else
  *set na2 "second name change"
  *set na $!{na1}${na2}
  *finish

But for the last code (above), it tells me that line 6 is
“invalid expression, couldn’t extract another token !{na1}{na2}”

[Lan]

${} is for displaying variables, & is used to concatenate two strings. You’ll want something like:

*set na na1&na2

There’s a useful article about concatenation on the wiki:

Concatenation

[Nahim_Kerman]

As our friend Lan already said you should replace

*set na $!{na1}${na2}

With

*set na2 $!{na2}
*set na1 $!{na1} 
*Comment setting na1 and na2 to uppercase
*Comment in the first letter
*set na ((na1&" ")&na2)

Try this and tell me if worked.