In choice end.session in before.choice event I have some verifications, if there is an error the user have to change some fields, but if I write choice.again() the command is canceled but the user cann't change the fields.
Which function have I use to do that?

I have the choice.again() insaid a function. The problem is solved change the function and making it a boolean function. I explain it:

OLD FUNCTION
--------------
choice.end.program:
before.choice:
my.function()

functions:
function my.function()
{
if ........ then
message(" Hello ")
choice.again()
endif
}


NEW FUNCTION
----------------
choice.end.program:
before.choice:
if my.function() then
message(" Hello ")
choice.again()
endif

functions:
function domain tcbool my.function()
{
if ........ then
return(true)
endif
return(false)
}