How to get/cut small message from error list

Hi experts,

I have made an application in SMP 2.3, which display Order detail.For this, i have used standard BAPI  for displaying the order list.it is working fine.When i am entering wrong data, it is also giving me error.

Now, my requirement is to get the proper message from this error list.

Please have a look on the below screen:

This error comes, when i click on the Header details button, without entering any order.Although, error is quite right, but as mobile screen is no so much large.So,my requirement is to display, exact error info. i.e.(Enter Order Number(as indicated in above screen)).

Please suggest.

Thanks,

Rohit