how to catch error of previous step in next step and print in log as output

I have got error Server not found, in next step I want to print it as lr_output_message in Ajax truClient,

in same step:

1.I take Releated Object tag I trace window (Add Related object) and add tag "Server not found"

in

2.next step I take catch error and in select Object Identification and try equate here Object Identification == server not found tag in previous step and want to take it as output in runtime log but could not get success

 It is printing Object Identification as error but in addition to this I want to print Server not found (error attached with this post)