Photoshop extension building not working for cs6, works for the rest

I am building an extension for photoshop the manifest file is as below:

<?xml version="1.0" encoding="UTF-8"?>
 
 
<ExtensionManifest Version="4.0" ExtensionBundleId="Kit" ExtensionBundleVersion="2.0.0"
  ExtensionBundleName="Kit" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <ExtensionList>
  <Extension Id="Kit.extension1" Version="2.0.0" />
  </ExtensionList>
  <ExecutionEnvironment>
  <HostList>
  <Host Name="PHSP" Version="[13.0,15.9]" />
  <Host Name="PHXS" Version="[13.0,15.9]" />
  </HostList>
  <LocaleList>
  <Locale Code="All" />
  </LocaleList>
  <RequiredRuntimeList>
  <RequiredRuntime Name="CSXS" Version="3.0" />
 
 
  </RequiredRuntimeList>
  </ExecutionEnvironment>
  <DispatchInfoList>
  <Extension Id="Kit.extension1">
  <DispatchInfo >
  <Resources>
  <MainPath>./index.html</MainPath>
  <ScriptPath>./Kit.jsx</ScriptPath>
  </Resources>
  <Lifecycle>
  <AutoVisible>true</AutoVisible>
  </Lifecycle>
  <UI>
  <Type>Panel</Type>
  <Menu>Beauty Retouching Kit</Menu>
  <Geometry>
  <Size>
  <Height>580</Height>
  <Width>250</Width>
  </Size>
  <MaxSize>
  <Height>580</Height>
  <Width>250</Width>
  </MaxSize>
  <MinSize>
  <Height>580</Height>
  <Width>250</Width>
  </MinSize>
  </Geometry>
  <Icons>
  <Icon Type="Normal">./pictures/thumb/Icon.png</Icon>
  <Icon Type="RollOver">./pictures/thumb/Icon.png</Icon>
  <Icon Type="DarkNormal">./pictures/thumb/Icon.png</Icon>
  <Icon Type="DarkRollOver">./pictures/thumb/Icon.png</Icon>
  </Icons>
  </UI>
  </DispatchInfo>
  </Extension>
  </DispatchInfoList>
</ExtensionManifest>

I tried this code for photoshop CC and CC 2014, it works for both but I couldn't get it to run for cs6 it gives the below error from the extension manager:

so isn't Version="[13.0,15.9]" correct? why would it not work for cs6? thanks in advance.