Most likely you installed the software directly onto those nodes instead of on the "software image". Then, after a reboot of the nodes, whatever you had installed on the regular node was written over by the usual software image. The software image is what is deployed from the head node to the regular nodes, and runs on the regular nodes.
So, installing software directly on to a particular bunch of regular nodes is not how you should install software to a category of nodes.
See the chapter "Post-Installation Software Management" for how you can place software onto nodes. The basic idea explained in that chapter is to put the software on the software image kept on the head node. The software image (what gets written out to the regular nodes on reboot during the provisioning process) is then provisioned to the regular node after a reboot.
A good idea is to divide nodes up into categories. A category is a group of regular nodes, for nodes that share the same configuration. See the chapter "Cluster Management With Bright Cluster Manager" for details on the concept of categories. If you assign nodes to a category that has a software image with the software suite on the image, then that category of nodes gets that suite installed on reboot.