bl cannot be resolved

[wangshuai_v7]

<%
String tname = request.getParameter("inputname");
String tpassword = request.getParameter("inputpassword");
if(tname !=null && tpassword!=null){
String bl = log.login(tname, tpassword, request);
if (bl == "true" ) {
%>


<script language="javascript">

<%=bl%>

</script>


.......myeclipse中配置tomcat服务器，运行时提示“bl cannot be resolved”。怎么回事呢？？？？？？？？？