Combo Undefined Error

Hello everybody!
I’m trying to attach Combo to a cell in a grid and load it dynamically.
I’ve tried different approaches but none of them works.

This happens when I try to do the following
If I do the following

var combo = gridData2.getColumnCombo(1);
      combo.setOptionWidth(300);        
      combo.clearAll();
      combo.enableFilteringMode(true);  
     uboptions = '<complete><option value="722003">722003|aaa</option><option value="733201">733201|bbb"</option><option value="xxxxxx">xxxxxx|not classified</option></complete>'
      //combo.load('<complete><option value="722003">722003|aaa</option><option value="733201">733201|bbb"</option><option value="xxxxxx">xxxxxx|not classified</option></complete>');
      combo.load(uboptions);

is OK with static initialization of var.

But when I change the method of getting uboptions var to ajax (and uboptions value remains the same as in the snippet before) I get the error when I focus on combo.
Last error I got is:

Undefined error Error 8070000c. dhtmlxgrid.js, line 9 col 15308.

I can change format of my xml, or do it in a json way - still the same

Thank you for help

Oh, the solution was quite simple. I have to exclude starting and finishing quote marks in my ajax procedure that fills uboptions variable