Plugin not detected by safari 5

My npruntime plugin works perfectly fine with FF 3.6+,chrome and opera. but safari 5 does not detect my plugin at all.I already have registry entries pointing to a valid location for my plugin and with appropriate mime types. surprisingly it works on safari 3 only ( not working on safari 4 even) can some please let me know if there is anything specific i should be doing to get my plugin detected by safari 开发者_StackOverflow4,5 ???

Do you have a description set? The one time I had that issue using FireBreath it turned out to be that I had an empty value for plugin description.