If you have Sybase 15.0 products, such as Adaptive Server Enterprise 15, install Sybase IQ 12.6 in a separate directory instead of the same $SYBASE directory, and set the SYBASE_OCS environment variable correctly for each product.
OCS 15.0 (Open Client /Server), requires changes in the environment that conflict with OCS 12.5. Because Sybase IQ 12.6 uses OCS 12.5, installing it in the same $SYBASE directory may cause problems for Sybase products that use OCS 15.0, such as Adaptive Server Enterprise 15.