Filter by Site block is not working in Apache solr multisite search..

After enabling the filter by site block when i try to search using apache solr multisite search, the Filter by site block doesn't show the site names and the sorting is also not done accordingly.
All it does is show me the links of the number of results found sorted according to the sites and when clicked on the result it goes to a blank search page..

As far as i've found out, $sites[$hash] is blank in the code below :

function apachesolr_multisitesearch_block
case 'hash':
$hashes[$active ? $countsort . $hash : 1 + $countsort . $hash] = theme('apachesolr_facet_item', $sites[$hash], $count, $path, $active, $unclick_link, $response->numFound);

I guess here is where the problem is.. there is value in $sites and $hash , but not in $sites[$hash]
and i feel that this is affecting the indexing of all the contents.. cos both the apache multisitesearch and apache search perform the same operation..!

And under
Site configuration › Apache Solr > Enabled filters ,
the multisite blocks, h , n , s , t which i have enabled and configured under Site building don't even show up.

Any clue..! pls help..

Subhasini