Multiple web-api Methods name start with 'Dele

Question

I am using Asp.net mvc4 web-api.

I have 2 web-api methods both with starting keyword "Delete" and throwing 500 internal server error.

//working fine

public HttpResponseMessage DeleteMenu(MenuModel objMenuModel)
{

}

not working - showing 500 internal server error

public HttpResponseMessage DeleteAllMenu(MenuModel objMenuModel)
{

}

DeleteAllMenu method not working as it is already DeleteMenu method. If I comment DeleteMenu related stuff then DeleteAllMenu is working other wise throwing 500 internal server error.