Event log error of soap web service in axapta to D365FO

 ComponentName CustomServices 

  exceptionMessage Microsoft.Dynamics.Framework.Services.Compiler.Soap.SoapServiceCompileException: Code compile failed. c:\Users\Admin58d4b701fe\AppData\Local\Temp\8af9311e31a44d709460cea11e26d22d\qadynl2j.0.cs(32,64) : error CS0101: The namespace 'Dynamics.AX.Application.Services.WLKSalesLineService' already contains a definition for 'WLKSalesLineService' at Microsoft.Dynamics.Framework.Services.Compiler.Soap.SoapServiceCompiler.CompileCode(SoapServiceCompileContext context) at Microsoft.Dynamics.Framework.Services.Compiler.Soap.SoapServiceCompiler.CompileService(String serviceGroupName, SoapServiceCompileContext context) at Microsoft.Dynamics.Framework.Services.Hosting.Soap.SoapXppServiceRoute.GetHostingInfo(String serviceGroupName) 

  infoMessage Exception while setting up the hosting info. 

Please comment your suggestion .

I'm getting this error in event log for one service:

error CS1503: Argument 1: cannot convert from 'Dynamics.AX.Application.WLKCustVendStatusContract' to 'Microsoft.Dynamics.Ax.Xpp.Set'

[

    SysEntryPointAttribute(true),

    AifCollectionTypeAttribute("_accountNum",Types::String),

    AifCollectionTypeAttribute("return",Types::Class, classStr(WLKCustVendStatusContract))

]

public WLKCustVendStatusContract VendorStatus(AccountNum     _accountNum)

{

    VendTable                   VendTable;

    WLKCustVendStatusContract   ret;

    VendTable = VendTable::find(_accountNum);

    if(VendTable)

    {

        ret = new WLKCustVendStatusContract();

        ret.parmCreditLimit(0);

        ret.parmCustVendorBlocked(VendTable.Blocked);

    }

    else

    {

        ret = null;

    }

    return ret;

}

if i add this method in service then getting error