NFS Mount Os400 to AIX

I am having an issue in one of my LPARs gettin a NFS mount between it, AIX and an Iseres LPAR, Os400. I get NFS Server xxxx not responding still trying. When I run the df commmand it says NFS Server xxxxx ok. Then shows the fs and then continiously puts out the about not responding error and the NFS Server xxx ok....FYI, I do have this nfs mount running fine between another iseries and pseries lpar.
Any ideas?