How to Apply theme to a sharepoint site using WCF service?

Question

I am trying to apply a theme to a sharepoint site. 
my method is as follows :


public void ApplyCustomeTheme(string url, string themeName)
        {
            using (SPSite oSite = new SPSite(url))
            {
                using (SPWeb oWeb = oSite.OpenWeb())
                {
                    System.Collections.ObjectModel.ReadOnlyCollection<ThmxTheme> oThemes =
                        ThmxTheme.GetManagedThemes(oSite);
                    // list out all themes of this particular site 
                    foreach (ThmxTheme oTheme in oThemes)
                    {
                        // Apply my custom theme to the current website 
                        if (oTheme.Name == themeName)
                        {
                            ThmxTheme.SetThemeUrlForWeb(oWeb, oTheme.ServerRelativeUrl);
                        }
                    }
                }
            }
        }




but when i try to run the WCF client i get the following error: 
Could not load file or assembly 'Microsoft.SharePoint.Search' or one of its dependencies. An attempt was made to load a program with an incorrect format.
I have included the 'Microsoft.SharePoint.Search' dll in the References. 


Can some one please explain me what is causing this ?. Is it because of serialization ?
Can i get a solution on this ?

---

Shoeb Sayyed