It doesn't like your vfp expression. Here's another example that should always work(spaces between < and % should not be in live version):

< %
local cadena
cadena= '123'% >
< %= cadena % >

>i do it a little test.
>i write this code and save as html
>
>\\ <%
> local cadena
> cadena= '123'
>
>
> <%= cadena \\
>
>however the form ever says
>Tipo de error:
>mergetext err#= 152 line= 368 Falta alguna expresión.152 Falta alguna expresión. .NULL. .NULL. .NULL. .NULL. .NULL. c:\iesoweb\practica\practica.dll (0x800A0098)
>c:\iesoweb\practica\practica.dll
>/Practica/default.asp, línea 6
>
>
>i only like test a block instruction and show values.
>
>thanks...