Please Use the following:
SCRIPT- CONDITION - DATAFLOW
Use a variable in the script and assign the value TRUE or FALSE based on your check in the script,
If check Passes $V_CHECK=‘TRUE’ otherwise assign it as FALSE.
Once that is done, use the condition object and check the value of $V_CHECK.
IF TRUE then proceed to Dataflow Else you can print a custom message like Condition not satisfied, Exit processing.