[SR-Users] can't assign values to $fU

From the online documentation:$fU - From URI username *$fU* - reference to username in URI of 'From' header It is R/W variable (you can assign values to it directly in configuration file) But i am no able to assign values to $fU. Has anyone experienced this? Snippet of code in the configuration file of mine and its respective logs showing that $fU is not getting overwritten. I have tried to hard code values to it assign variables to it, all to no avail. configuration file code snippet: xlog("L_INFO", "[$ci] from header username pre mod: $fU"); $fU = "5555555555"; xlog("L_INFO", "[$ci] from header username post mod: $fU"); Logfile snippet: INFO: (s) [7EAB8FECD723E8444E36C659F331068B41EC6BB0] from header username pre mod: 3224567880 INFO: (s) [7EAB8FECD723E8444E36C659F331068B41EC6BB0] from header username post mod: 3224567880 Thanks, Karthik