SAP adapter...SAP login problems

I seem to be getting a strange error when I set up the SAP adapter to login to our SAP system.

For some reason when I initially setup the parameters(the parameters are definitely correct) the adpater will not login, throwing the following error…

Message:You are not authorized to logon to the target system (error code 2).
Service:sap.admin:SystemInfo

Looking a little deeper at the RFC log, I get this…

T:330 ======> You are not authorized to logon to the target system (error code 2).
T:330 <* RfcReceive [18] : returns 3:RFC_SYS_EXCEPTION
T:330 <* RfcCallReceive [18] : returns 3:RFC_SYS_EXCEPTION

After a period of time, usually a week or so, this error clears and the adapter logs in, no problem at all, without any change to the setup

Has anyone else experienced this? Does anyone know how to correct it?

B