Opatch: ApplySession failed during prerequisite checks: Prerequisite check "CheckApplicable" failed.

Trying to apply a patch:

/opt/oracle/fmw11_1_1_5/oracle_common/OPatch/opatch apply -jdk /opt/oracle/java/ -invPtrLoc /opt/oracle/fmw11_1_1_5/oraInst.loc

Invoking OPatch 11.1.0.8.2

Oracle Interim Patch Installer version 11.1.0.8.2

Copyright (c) 2010, Oracle Corporation.  All rights reserved.

Oracle Home       : /opt/oracle/fmw11_1_1_5/oracle_common

Central Inventory : /opt/oracle/orainventory

   from           : /opt/oracle/fmw11_1_1_5/oraInst.loc

OPatch version    : 11.1.0.8.2

OUI version       : 11.1.0.9.0

OUI location      : /opt/oracle/fmw11_1_1_5/oracle_common/oui

Log file location : /opt/oracle/fmw11_1_1_5/oracle_common/cfgtoollogs/opatch/opatch2014-01-31_11-44-50AM.log

Patch history file: /opt/oracle/fmw11_1_1_5/oracle_common/cfgtoollogs/opatch/opatch_history.txt

OPatch detects the Middleware Home as "/opt/oracle/fmw11_1_1_5"

ApplySession applying interim patch '17279791' to OH '/opt/oracle/fmw11_1_1_5/oracle_common'

Running prerequisite checks...

Prerequisite check "CheckApplicable" failed.

The details are:

Patch 17279791: Required component(s) missing : [ oracle.osb.top, 11.1.1.5.0 ]

ApplySession failed during prerequisite checks: Prerequisite check "CheckApplicable" failed.

System intact, OPatch will not attempt to restore the system

OPatch failed with error code 74

Remember, you should ALWAYS set these variables:
export MW_HOME=/opt/oracle/fmw11_1_1_5/
export ORACLE_HOME=/opt/oracle/fmw11_1_1_5/osb
export JDK_HOME=/opt/oracle/java

(thanks to Monica Crugnola for reminding me this)