Validate Signature field is signed

I have given up.  I have checked all the different discussions on this and I can't get it to work!  Here is my code.

What am I doing wrong !  Please help

var oDoc = event.target;

var oState = event.target.getField("Main.DeptHeadApproval").signatureValidate();  

{if (oState == 0)

    {messagetext=messagetext + "\tDirector/Department Head Approval\n";

    errorcount = errorcount + 1;}   

if (errorcount == 0)

{OfficeUse.presence = "visible";

oDoc.mailDoc({

        bUI: true,

        cTo: "EnterpriseRisk@uillinois.edu",

        cCc: UserEmail.rawValue + ";" + DeptHeadEmail.rawValue,

        cSubject: "JCAD Risk User Set Up",

        cMsg: "",

        });}

else {xfa.host.messageBox("Missing Required Field(s):\n"+ messagetext);}}