JSP Error

Exception:

java.lang.StringIndexOutOfBoundsException: String index out of range: -1
	at java.lang.String.substring(String.java:1591)
	at rs.system.Browser._setBrowserInfo(Browser.java:119)
	at rs.system.Browser.(Browser.java:42)
	at rs.component.TagInputButton.getString(TagInputButton.java:125)
	at rs.component.TagInputButton.getString(TagInputButton.java:111)
	at rs.component.TagInputButton.getString(TagInputButton.java:108)
	at component.button.Bbookingrevision_inquiry_NK._jspService(Bbookingrevision_inquiry_NK.java:104)
	at oracle.jsp.runtime.HttpJsp.service(HttpJsp.java:117)
	at oracle.jsp.app.JspApplication.dispatchRequest(JspApplication.java:182)
	at oracle.jsp.JspServlet.doDispatch(JspServlet.java:203)
	at oracle.jsp.JspServlet.service(JspServlet.java:136)
	at javax.servlet.http.HttpServlet.service(Unknown Source)
	at oracle.jsp.provider.Jsp20RequestDispatcher.include(Jsp20RequestDispatcher.java:54)
	at oracle.jsp.runtime.OraclePageContext.include(OraclePageContext.java:398)
	at jsp.RS01010P._jspService(RS01010P.java:232)
	at oracle.jsp.runtime.HttpJsp.service(HttpJsp.java:117)
	at oracle.jsp.app.JspApplication.dispatchRequest(JspApplication.java:182)
	at oracle.jsp.JspServlet.doDispatch(JspServlet.java:203)
	at oracle.jsp.JspServlet.service(JspServlet.java:136)
	at javax.servlet.http.HttpServlet.service(Unknown Source)
	at org.apache.jserv.JServConnection.processRequest(JServConnection.java:317)
	at org.apache.jserv.JServConnection.run(JServConnection.java:188)
	at java.lang.Thread.run(Thread.java:479)