Can't openURL in a popup window from a published form

Can't openURL in a popup window from a published form

I have several published  forms (no login required) that I'm accessing via their permalink url's.  A user-action in Form 1 calls openURL and sends parameters to Form 2 in order to pre-populate some fields. After closing Form 2, I then need to return to Form 1 to continue. (I'm doing this since ZOHO can't send field values via "add new"for a look-up field !!!)

If I am logged in: Using openURL(form2sPermalink, "popup window", <dimensions>) works, although I have to manually close the popup window. 

However, if I'm NOT logged in, the pop-up window does not open. 

- I've tested each form separately and can enter data without being logged in. So my published permalinks are OK.

- Attempting other window options in openURL(<string>, <window type>):
      - "popup window" - Nothing opens.
      - "open window" - Form 2 opens in the same tab, so I am unable to return to Form 1 to continue.
      - "parent window" and "same window" act the same as 'open window'.
      - (not using iFrames).

Any suggestions?