hqapi problem

Hello all!

how to fix this error?

C:\HQ_Webserver\server-4.5\hqapi1-client-4.0.0\bin>hqapi.bat agent list
Error running command: Host name may not be null
java.lang.IllegalArgumentException: Host name may not be null
        at org.apache.commons.httpclient.HttpHost.<init>(HttpHost.java:68)
        at org.apache.commons.httpclient.HttpHost.<init>(HttpHost.java:107)
        at org.apache.commons.httpclient.HttpMethodBase.setURI(HttpMethodBase.ja
va:280)
        at org.hyperic.hq.hqapi1.HQConnection.runMethod(HQConnection.java:223)
        at org.hyperic.hq.hqapi1.HQConnection.doGet(HQConnection.java:101)
        at org.hyperic.hq.hqapi1.BaseApi.doGet(BaseApi.java:55)
        at org.hyperic.hq.hqapi1.AgentApi.getAgents(AgentApi.java:111)
        at org.hyperic.hq.hqapi1.tools.AgentCommand.list(AgentCommand.java:101)
        at org.hyperic.hq.hqapi1.tools.AgentCommand.handleCommand(AgentCommand.j
ava:79)
        at org.hyperic.hq.hqapi1.tools.Shell.dispatchCommand(Shell.java:202)
        at org.hyperic.hq.hqapi1.tools.Shell.main(Shell.java:217)