Actually, I don't know the main cause of the problem, but to resolve the issue I've done the following:
- created a new file: profiledStartScript.bat outside the weblogic server's bin directory.
added the following lines:
set DOMAIN_HOME=C:/Oracle/Middleware/user_projects/domains/myDomain
set JAVA_OPTIONS=%JAVA_OPTIONS% -agentpath:C:\PROGRA~1\jprofiler7\bin\windows-x64\jprofilerti.dll=port=8849
call "%DOMAIN_HOME%\bin\startWebLogic.cmd"
and that did the trick.