[PHP] syntax

[Wade Halsey]

Hi

I need to name a file like this
$fp=fopen('echo $agentcode' .'CyberTrac.ctr', "w");

the file gets named echo $agentcodeCyberTrac.ctr, now I want a real value in 
$agentcode, there is a value in there so it must be my syntax, anyone help?

TIA
Wade