How do we run the test steps in Load UI in a certain sequence if needed

Hi,

I have got a couple of questions.

1: How do we run the test steps in Load UI in a certain sequence if needed?

2: I have a test step that keeps failing because the service it hits fails 30 % of the the times and that service isnt the part of our project.

The problem is the load test is running the same test concurrently for that single account e.x. 123. so it keeps hitting the account 123 and that results a error rate of 30 %. Limitations are I  have got a limited amount of data to play with and the Load UI keeps running the same test result multiple times. Is there any way to deal with this or handle this?

 I have introduced think time but that isn't helping much.

Looking forward to some helpful replies. :)

Thanks 

Fez