How to calling webmethod by conventional javascript?

I have modified c# .net code like this.

1.a webmothod in some_name.asmx

[WebMethod]

public string WsGetBasicPremiumStandard(

string sGACode, string sVehicleType, string sInsurePlan, string sCC, string sKilo, string sSeat,

string sMake, string sModel, string sCarAge, string sIsCombine, string sEffDate, string sExpDate,

string sMakeModelCount, string userid, string channel, string sOwnDamage, string sDeduct,

string sTypeOfDriver, string sIsAccessory, string sSpecialPlan, string sDeductPD, string YearReg,

string policyType, string sInsureType, string sGroupOfPlan, string agentCode, string MLM_MemberNO,

string sBatchType, string registerNo, string chassisNo, string planVAO, string replacePolicy,

bool PhotoFeeFlag, bool violenceFlag, bool cctvFlag, string coverageRY,string Pr)

{

...

}

I modified this method by add "string Pr" parameter.

2.I have called this webmethod from CallService.js as below.

some_name.WsGetBasicPremiumStandard(

sGACode, sVehicleType, sPackage, sCC, sKilo, sSeat, sMake, sModel, sCarAge, sIsCombine,

sEffDate, sExpDate, sMakeModelCount, userid, channel, OwnDamage, Deduct, TypeOfDriver,

sIsAccessory, sSpecialPlan, sDeductPD, sYearReg, sProductType, sInsureType, sGroupOfPlan,

agentCode, MLM_MemberNO, sBatchType, registerNo, chassisNo, planVAO, replacePolicy,

PhotoFeeFlag, violenceFlag, cctvFlag, coverageRY, "N",

onLoadSuccess, onLoadError)

I pass value "N" for "Pr" parameter but i get error

Sys.Net.WebServiceFailedException: The server method 'WsGetBasicPremiumStandard' failed with the following error: System.InvalidOperationException-- Invalid web service call, missing value for parameter: 'Pr'.

anybody help me?

thank forward.

Thakerng.