The timing of an SSIS Data Flow Commit

Question

I am using an SSIS dataflow to copy data from a source table "s" to a target table "t", which is empty. For the very next step after the dataflow, I have a "Exec SQL Script" that runs a delete statement that deletes from a table "z" where the recently copied data exists in table "t". What I have been noticing is that the delete statment appears to be firing prior to the data fully committing in the previous dataflow step. Sometimes not all the data is in table "t" and the result of the delete is incorrect. Is there a way to guarentee the dataflow has completed and committed prior to executing the next step? Or is this bug?