Solution : https://service.sap.com/sap/support/notes/654717 (SAP Service marketplace login required)
Key words : 
protocol adapter br tools trigger errors, location brdbconnect-2work processes issue, error => oci-call 'olog' failed, correct net8 configuration files, incorrect net8 configuration files, br301w sql error -12538, earlier release date, ora-12538 error message, terms tns-12538 reason, older oracle home
Related Notes : 
       
| 602843 | Environment settings for R/3/Oracle on UNIX | 
| 562403 | FAQ: Oracle Net | 
| 556232 | Environment settings for R/3/Oracle on Windows | 
| 445038 | Problems when accessing Net8 configuration files |