Model Creation

Dear Experts,

When I try to create a model using adaptive RFC I am unable to login to the R3 system. The login details are correct and the user name also exits in the system. But I keep getting the error

Name or password is incorrect {repeat logon} 

and some times

User not authorized. Session terminated

for the same user id. It has sap_all authorization.

I have check the logon details and they are correct. Could this be because of SLD configuration? Please clarify.

Thanu