Please post your Model Class.
To check the errors in your ModelState
use the following code:
var errors = ModelState
.Where(x => x.Value.Errors.Count > 0)
.Select(x => new { x.Key, x.Value.Errors })
.ToArray();
OR: You can also use
var errors = ModelState.Values.SelectMany(v => v.Errors);
Place a break point at the above line and see what are the errors in your ModelState
.