SAP Message XS011 - Version & incompatible with version used

Diagnosis
The version specified when calling RFC &V1& is incompatible with theone used in R/3.

System Response
The RFC was not accepted; the message was not received.

Procedure
You are using a version that is incompatible with the communicationsystem (this is shown in the first two digits of the version number:R/3 = &V2&, RFC = &V1&). Notify your system administrator and import anew Release on one side.