[flexcoders] String syntax question

[candysmate]

I must be going (more) nuts, because I cannot figure out why my
Bindable public var:

[Bindable]
public var locateString:String;

which gives the correct value to:

<mx:TextInput x="258" y="224" text="{locateString}"/>

gives:

SELECT * from nominal WHERE (account = 'null')

when I build a string with:

 var sql:String = "SELECT * FROM nominal WHERE (account = '" +
locateString + "')"

inside a private function.

Help (please)!