A frequently error is coming in the Code and error message of that error is

At least one recipient is required, but none were found

and Stack trace of that error is given below .

at System.Web.Mail.SmtpMail.LateBoundAccessHelper.CallMethod(Object obj, String methodName, Object[] args) at System.Web.Mail.SmtpMail.CdoSysHelper.Send(MailMessage message) 
at System.Web.Mail.SmtpMail.Send(MailMessage message) 
at MFActivityPlanning.clsCommons.SendEmail(String sToMailAddr, String sSubject, String sMessage, MailFormat format, String sFromMailAddr)

pls help me, how can fix it?