Custom Image Field On Custom Estimate Form

Hi,
I've created a custom estimate form and a custom image field (type:image, id:custbody5).This field will contains customer image. I've created a suitescript for customer field changes, but when i execute it, custom image field is null!
Please help me!

 function changeField(type,fldname)  {  if (fldname == 'entity')   {    if (nlapiGetFieldValue('entity') != null)    {     var filters = new Array();     filters[0] = new nlobjSearchFilter('entityid',null,'contains','entity',null);     filters[1] = new nlobjSearchFilter('image',null,'isnotempty');     var columns = new Array();     columns[0] = new nlobjSearchColumn('image');             var customer = nlapiSearchRecord('customer',null,filters,columns);          if ((customer != null) && (customer.length > 0))     {      var image = customer[0].getValue('image');      nlapiSetFieldValue('custbody5',image);     }     else     {      nlapiSetFieldValue('custbody5',null);     }                       return true;    }       }  }