Query and problems on soap ui pro test steps

Hi,

I have a testsuite with testcase and with the following test steps:

Test Step 1: Groovy script
Test step 2: Datasource test step (disabled)
Test step 3: Request test step (disabled)
Test Step 4: Property Transfer (disabled)
Test step 5: Data sink (disabled)
Step 2 to 5 is disabled because I make use of the groovy script to run them.

The groovy script will do the following:
   do a iteration of say 2 times{

      a. run datasource test step
      b. run request test step
      c. run transfer property step
      d. run datasink step

}

Detailed explanation on the relationship of step a to d:
For the datasource test step, it will retrieve a record from db and its record values will be passed to the request test step.
For the request test step, it will fire a request and get a respond.
The response value would then be transferred to the datasink test step using the property transfer test step.
The datasink test step will be inserting or updating the response value to the DB.
This sequence should be done 2 times.

Question 1:
When I run the testrunner, it was throwing a NullpointerException error on datasource step(which means it did not execute the step), why is it so?

Question 2 (which link to Question 1):
If I never use the testrunner, I run the groovy script manually it will execute all my teststeps that is called in the groovy script. However, instead of executing step a to d in sequence 2 times, it execute each step 2 times. Why is it so? Also, why running the testrunner it will not work but if I run the groovy script it will?

Kindly reply to my questions and also how should I go upon resolving this problem?

Thanks.