Problem in uninstallation:LifeCycleDesigner7.1

I have Adobe Live Cycle Designer 7.1 installed in system. Now i need to install Adobe Live Cycle Designer 8. Before that i want to uninstall 7.1. But i could not uninstall 7.1 (through ADD OR REMOVE PROGRAMS), it is giving error message
"Failed to open /parse setup script. Please check if the script file 'setup/NwSapSetp.xsc' exists"
But 'setup/NwSapSetp.xsc' file is present in the system in location 'C:\Program Files\SAP\SapSeup\setup'.
If i open C:\Program Files\SAP\SapSeup\setup\NwSapSetp.exe it is giving same error.
I tried to uninstall using string
"C:\Program Files\SAP\SAPsetup\setup\NwSapsetup.exe" /product:"ALD" /uninstall /noRestart"
But it is giving same error.
Can any one help in this....