Searching in solr doesn't retrieve data

Question

I've indexed two Mysql tables in a SolR core and I'm currently trying to launch requests from the backend (administration panel provided by SolR).

Problem : When I type nothing in "q" parameter, Solr gives back all the results it has in its index. But when I type a word (that exists in many of the fields indexed in the same typography) Solr doesn't give back anything.

More infos : Here's an example of the query URL when searching for rue:

http://127.0.0.1:8983/solr/core_test/select?q=rue&wt=json&indent=true

And when searchin with an empty 'q' value :

http://127.0.0.1:8983/solr/core_test/select?q=*%3A*&wt=json&indent=true

I've indexed the field in the <fields> tag like this :

<field name="ts_variable1" type="text" indexed="true" stored="true"/>

<field name="ts_variable2" type="text" indexed="true" stored="true"/>

<field name="ts_variable3" type="text" indexed="true" stored="true"/>

I've used a data-import handler for mysql. (solr-dataimporthandler-.*.jar) (sorry I don't remember what the wildcard is for). and configured it like :

<requestHandler name="/dataimport"  class="solr.DataImportHandler">
  <lst name="defaults">
    <str name="config">data-config.xml</str>
  </lst>
</requestHandler>