Solution : https://service.sap.com/sap/support/notes/830528 (SAP Service marketplace login required)
Key words : 
function module group srfc, password logon failed counter, previous rfc system calls, logon attempts fail, downward-compatible kernel, patch number 1070see, patch number 1003see, patch number 69see, rfc library version 6, rfc library
Related Notes : 
       
| 828000 | Rfc Patch Collection 11 2005 | 
| 774406 | |
| 664679 | Installing 6.40 kernel in SAP WEB AS 6.10/6.20 | 
| 318846 | Installing the 4.6D kernel in 4.6A/B/C SAP systems | 
| 19466 | Downloading SAP kernel patches |