Hello,

I have written a controller to prepopulate a visualforce page.  The controller works fine in sandbox, and when I run through the steps is prepopulates perfectly in the browser but when I try to run tests it tells me the field is not writable.  I seem only to have this problem with lookup fields, when I remove those it compiles, tests and deploys fine.  I tried also prepopulate those using the url but visualforce pages have very odd field ids and the url seems not to understand them.  Does anyone have any suggestions?  Here' s my controller:

public class addContactAffiliation {
 Public npe5__Affiliation__c affil;
 Public Contact contact;
 Public string AccountID = System.currentPagereference().getParameters().get('AccountID');
 Public string ContactID = System.currentPagereference().getParameters().get('ContactID'); 
 
    public npe5__Affiliation__c getAffil() {
      if(affil == null) affil = new npe5__Affiliation__c();
      contact = [select Name, LastName, id, npe01__WorkEmail__c,
                      npe01__Workphone__c, npe01__AlternateEmail__c,mobilephone,
                      otherphone, work_fax__c, mailingcity, mailingcountry,
                  mailingpostalcode, mailingstate, mailingstreet from contact where Id =:      

    contactId];
           
          affil.npe5__Contact__c = contact.name;
          affil.email__c = contact.npe01__WorkEmail__c;
          affil.office_phone__c = contact.npe01__Workphone__c;
          affil.email_2__c = contact.npe01__AlternateEmail__c;
          affil.cell_phone__c = contact.mobilephone;
          affil.alt_phone__c = contact.otherphone;
          affil.street__c = contact.mailingstreet;
          affil.city__c = contact.mailingcity;
          affil.state__c = contact.mailingstate;
          affil.zip__c = contact.mailingpostalcode;
          affil.country__c = contact.mailingcountry;
          affil.fax__c = contact.work_fax__c;
             
      return affil;
   }

Really appreciate your help - it's so frustrating to get to this point and not to be able to prepopulate the most important field!