dotNET builder error

when a try to use an assembly that I have created using buider dotNET I got an error in visual studio 2010, specifically, this error

An unhandled exception of type 'System.BadImageFormatException' occurred in mscorlib.dll

Additional information: Could not load file or assembly 'MWArray, Version=2.12.0.0, Culture=neutral, PublicKeyToken=e1d84a0da19db86f' or one of its dependencies. Foi feita uma tentativa de se carregar um programa com um formato incorreto.

can someone give me a solution?

[Walter Roberson]

The Portugese portion translates as "An attempt was made to load a program with an incorrect format."