VSIX Show ContextMenu after Multi-File Selection in Two or More Projects

Question

I'm building an extension for VSIX.

After selecting a file in the Solution Explorer, I am displaying my menu in the ContextMenu.

<CommandPlacements>
    <CommandPlacement guid="guidCopyTextSelectedFilesCommandPackageCmdSet" id="MyMenuGroup" priority="0xF00">
        <Parent guid="guidSHLMainMenu" id="IDM_VS_CTXT_ITEMNODE" />
    </CommandPlacement>
    <CommandPlacement guid="guidCopyTextSelectedFilesCommandPackageCmdSet" id="MyMenuGroup" priority="0xF00">
        <Parent guid="guidSHLMainMenu" id="IDM_VS_CTXT_PROJNODE" />
    </CommandPlacement>
    <CommandPlacement guid="guidCopyTextSelectedFilesCommandPackageCmdSet" id="MyMenuGroup" priority="0xF00">
        <Parent guid="guidSHLMainMenu" id="IDM_VS_CTXT_FOLDERNODE" />
    </CommandPlacement>
</CommandPlacements>

But the problem is that it doesn't show up when I select files from more than one project.

I can't easily find a way to make them visible, please help me