找不到指定的模块 - 64位dll

I had the 32 bit dll which is written using Native C, when I tried compiling with VC++(VS2008) for converting the dll to x64 by changing the platform it compiled. But when I tried to access the dll from my C# application which is also 'x64' platform it fails to load the dll. I used Dllimport for linking the dll with my application.I had the 32 bit dll which is written using Nat