LogiCORE IP 7 Series FPGAs Integrated Block v1.4 for PCI Express data sheet states that XC7V1500T and XC7V2000T are not available in the ISE tool flow. However, the core is still enabled and can be generated when selecting these devices in CORE Generator.
This is a known issue and will be fixed in a future release of the core. XC7V1500T and XC7V2000T devices are not supported in ISE Design Suite. They are supported only in Vivado 2012.1 Design Suiteand onwards.
NOTE: "Version Found" refers to the version the problem was first discovered. The problem might also exist in earlier versions, but no specific testing has been performed to verify earlier versions.
05/20/2012 - Initial release