In reply to abdulhafiz.oa:
Why you are starting the sequence in the base sequence?. Going this way you loose the ability to control the sequence execution. In the base you should model the behavior what this sequence is doing. And you should start it from your test. This is the recommended way.
Regarding the seq_item execution you are right. A sequencer can execute a seq_item. Befor calling start_item you should call create_item. See the UVM Ref Manual.