问ant目标vssget不工作

EN

D:\release>ant vssbuild Buildfile:
build.xml

vssbuild:    [vssget] 'ss' is not
recognized as an internal or external
command,    [vssget] operable program
or batch file.

BUILD FAILED
D:\release\build.xml:141:
Failed executi ng: ss Get $(project)
-GLD:\release\$(lo
calpath) -I-  -R  
-Y$(vssusername),**************   With a return code of 1

<property name="localpath" value="checkout" />
    <property name="project" value="$/NewGen/NextGenComm" />
    <property name="vssusername" value ="ganukep" />
    <property name="vsspassword" value ="123"/>
    <property name="projectlabel" value = "2011.05.20_V1.0.0" />
    <target name="vssbuild"> 
        <vssget vsspath="$(project)" 
              localpath="$(localpath)" 
              recursive="true" 
              login="$(vssusername),$(vsspassword)"
        />     
     </target>