Role Provider error in web.config - asp.net-mvc-3

Question

My application is in Asp.Net MVC3, my application was running perfectly but all of a sudden i'm getting an error in my Web.Config in my role manager tag.
Below is my RoleManager tag of web.config
<roleManager defaultProvider="MASSIARoleProvider" enabled="true" cacheRolesInCookie="true">
<providers>
<clear />
<add name="MASSIARoleProvider" type="MASSIA.Helpers.MASSIARoleProvider, MASSIA" connectionStringName="MASSIAEntities" />
</providers>
</roleManager>
Below is the error i'm getting directly when i run my application:
[updated Error Image]
I have a file MASSIARoleProvider.cs in my solution in the directory Helper.
Below is Heirarchy of my RoleProvider file.
--> Massia --> Helpers --> MASSIARoleProvider.cs
My solution was executing perfectly but i'm getting this error all of a sudden.

Answer 1

<roleManager defaultProvider="MASSIARoleProvider" enabled="true" cacheRolesInCookie="true">
<providers>
<clear />
<add name="MASSIARoleProvider" type="MASSIA.Helpers.MASSIARoleProvider" connectionStringName="MASSIAEntities" />
</providers>
</roleManager>
Attemp 2:
Check for your MASSIARoleProvider file and see whether the Solution name and references used are perfectly correct.
Attempt 3:
The last and least recommended.
Create a new solution, if and only if your solution is in the beginning stage and try to reconfigure the RoleProvider. Once it solved the issue for me, I made a new solution, added the existing files to the news solution and executed the new solution and it executed perfectly. I did not made any change to the code, i just included the existing files from the old solution to the new one.