ASP Web Admin Tool - Security error

I am trying to click the Security tab of my Web Administration Tool (Trying to set admin roles) and its giving me the error .. I have tried executing aspnet_regsql.exe in CMD and i'm getting a SQL database error when I try it. I have confirmed i can log onto my database so It's not the database.

There is a problem with your selected data store. This can be caused by an invalid server name or credentials, or by insufficient permission. It can also be caused by the role manager feature not being enabled. Click the button below to be redirected to a page where you can choose a new data store.

The following message may help in diagnosing the problem:

Could not load file or assembly 'Microsoft.CodeDom.Providers.DotNetCompilerPlatform, Version=1.0.3.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. An API call exited abnormally. (Exception from HRESULT: 0x800300FA (STG_E_ABNORMALAPIEXIT))