I created my own module and I need to add search feature to it so that I make My FeatureController Extend ModuleSearchBase and implement GetModifiedSearchDocuments method then Update My dnn file by add 

<supportedFeatures>

<supportedFeature type ="Searchable" />

</supportedFeatures> 

then I Make My module IsSearchable from the portal.

but it does not work , What I should do ?