Dynamic links with a Decorator

Hi,
I tried to generate dynamic links containing more than one parameter using Decarator as below

public String getDtlLink4()
{
TestClass Dtl= (TestClass)getCurrentRowObject();
String Grp= (Dtl.getGroupName());
String Appl= (Dtl.getApplicationName());
String Job= (String.valueOf(Dtl.getJobName()));
String RunId= (String.valueOf(Dtl.getProcessRunId()));
return "<a href=\"TestAction.action?groupName=" +Grp+ "&applicationName=" +Appl+ "&jobName=" +Job+ "&RunId=" +RunId+"\">Details</a>";
}

JSP has
<display:column property="dtlLink4" sortable="false" title="Details" />

Every thing works fine. But in the web page the table will have values for Column Details as below string

<a href="TestAction.action?groupName=ABC&applicationName=XYZ&jobName=JOB1&RunId=11">Details</a>

It should be displayed as hyperlink for Details. when i click on that link it should invoke the action. I tried to give autolink="true" in Display:Column . But it didn't work.
Any help about this problem.