package error

I am quite unfamiliar with compiling with sbt package. What could be my issue here? It seems like the scala library is wrong, but where do I look for the scala jar?

thanks,
rob

"$ ./sbt package
[info] Loading project definition from /Users/reefedjib/Desktop/rob/comp/workspace/kafka/project
[info] Set current project to Kafka (in build file:/Users/reefedjib/Desktop/rob/comp/workspace/kafka/)
[info] Compiling 52 Scala sources and 1 Java source to /Users/reefedjib/Desktop/rob/comp/workspace/kafka/core/target/scala-2.8.0/classes...
[error] class file needed by TopicAndPartition is missing.
[error] reference type Serializable of package scala refers to nonexisting symbol.
[error] one error found
[error] (core/compile:compile) Compilation failed
[error] Total time: 5 s, completed Jun 6, 2013 11:47:38 AM"