[Serusers] variables with avp_check

[Joao Pereira]

Hello, I want to use variables in ser.cfg and I m trying to use avpops 
for it

# first by giving the variable "var" the value "internal"
# string mysar = internal;
avp_write("internal", "s:myvar");

# and checking this variable later:
# if (myvar = internal)
if (avp_check("s:myvar", "eq/internal/i")){

But this never enters in this if, can someone tell me the way to do it?
Or where is some documentation about avpops (iptel.org/ser doesnt have).
Thanks
Joao Pereira