Quote:i have posted entire error message
No, though that's useful, it tells us nothing that lets us answer your problem.
Remember that we can't see your screen, access your HDD, or read your mind - we only get exactly what you type to work with.
And we have no access to your code, your config file, or your DB - so we can't tell at all what exactly is going on, and you need that to work out what the problem might be.
So, it's going to be up to you.
Fortunately, you have a tool available to you which will help you find out what is going on: the debugger. If you don't know how to use it then a quick Google for "Visual Studio debugger" should give you the info you need.
Put a breakpoint on the first line in the function, and run your code through the debugger. Then look at your code, and at your data and work out what should happen manually. Then single step each line checking that what you expected to happen is exactly what did. When it isn't, that's when you have a problem, and you can back-track (or run it again and look more closely) to find out why.
Sorry, but we can't do that for you - time for you to learn a new (and very, very useful) skill: debugging!