Problem with 'sint' in "More Like This" feature

[vi...@8kmiles.com]

Hi,

I am using the "More Like This" feature. I have configured it in 
solrconfig.xml as a dedicated request handler and I am using SolrJ.
It's working properly when the similarity fields are all text data types.
But when I add a field whose datatype is 'sint', it's throwing an exception.
Exception - Caused by: org.apache.solr.common.SolrException: 
For_input_string_?javalangNumberFormatException_For_input_string_?

Any help / suggestion is much appreciated.

Thanks,
Vijay