Probably MPLS LSP is “broken” on area border router. There is no limitation for VPLS to work between routers in different areas - actually MPLS (and therefore VPLS) does not care what IGP is used to exchange routes. What matters is that there must be “complete” MPLS LSP between VPLS endpoints and usually it means that all routers between VPLS endpoints MUST have /32 routes to VPLS endpoints. Make sure that area border routers are properly distributing /32 routes for VPLS endpoints into neighboring area.
To some extent this has been explained here: http://forum.mikrotik.com/t/why-cant-i-use-24-routes-for-ldp-and-vpls/33349/1