Custom Workflow step is not visible in dropdown

I have created custom workflow process step but  I dont see that custom workflow step in dropdown in workflow model page.

my workflow class is as follows

@Component(
        immediate = true,
        service = WorkflowProcess.class,
        property = {
                "process.label=org: Reduce Image Resolution"
        }
)
public class ReduceImageResolutionProcess implements WorkflowProcess {

I have similar another workflow step which is visible in dropdown. what could be the problem?