Autocomplete with jquery json. Why this error heppens????

Autocomplete with jquery json. Why this error heppens????

The program works on local but not works on server.Why??????

[WebMethod]

public List<string> GetAutoCompleteData(string prefixText)
{ 

...

Server Error in '/' Application.

Unknown web method GetAutoCompleteData.
Parameter name: methodName

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. 

Exception Details: System.ArgumentException: Unknown web method GetAutoCompleteData.
Parameter name: methodName

Source Error: 







An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.


Stack Trace: 



[ArgumentException: Unknown web method GetAutoCompleteData. Parameter name: methodName] System.Web.Script.Services.WebServiceData.GetMethodData(String methodName) +539974 System.Web.Script.Services.RestHandler.CreateHandler(WebServiceData webServiceData, String methodName) +10 System.Web.Script.Services.RestHandler.CreateHandler(HttpContext context) +159 System.Web.Script.Services.RestHandlerFactory.GetHandler(HttpContext context, String requestType, String url, String pathTranslated) +62 System.Web.Script.Services.ScriptHandlerFactory.GetHandler(HttpContext context, String requestType, String url, String pathTranslated) +47 System.Web.MaterializeHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +334 System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +184


Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.0.30319.272 

Please help

Thanks