Exception from HRESULT: 0x80131044

I got Unknown build error quoted below:

Severity Code Description Project File Line Suppression State Error Unknown build error, 'Could not load file or assembly 'Amisys.Data, Version=5.1.1.3, Culture=neutral, PublicKeyToken=null' or one of its dependencies. A strongly-named assembly is required. (Exception from HRESULT: 0x80131044) Line 8 Position 32.'

I built 'Amisys.Data' (I checked on Sign the assembly) with Signing when I built first and and built again after deletion of strong named key and unchecking Sign the assembly unchecked, means cleared all strong named assembly.

When I compile the executable assembly which unchecked reference added, I got error like above.

Is there any way to clear that out and make it work?

Regards Joon