monodevelop - 983 Error Reference Assembly

I just Installed Unity with Mono Develop .. Whenever I Try to build Mono Develop Keep Throwing this warning

C:\Windows\Microsoft.NET\Framework\v4.0.30319\Microsoft.Common.targets(5,5): Warning MSB3644: The reference assemblies for framework

".NETFramework,Version=v4.5" were not found. To resolve this, install the SDK or Targeting Pack for this framework version or retarget your application to a version of the framework for which you have the SDK or Targeting Pack installed. Note that assemblies will be resolved from the Global Assembly Cache (GAC) and will be used in place of reference assemblies. Therefore your assembly may not be correctly targeted for the framework you intend. (MSB3644) (Project01)

Please Let me know How to tackle this warning .. when I try to install .net framework 4.5 system says you already have install .. So i reinstall JTK and Mono develop but still this warning appear