Combo boxes in Grid

This seems like a simple solution, but I know I’m missing something easy. I’m trying to make a combo box that has an item already something selected based off an entry in the database.

Example:
A row in my database has Server Ip, Server Name,Backup Server,Path,Retention Day(s),Tape Frequency,Backup Frequency,Type, and Retention Profile. When populating my dhtmlGrid, Everything is is just a ro field except Retention Profile. It is a coro. Now whatever is in my database for the Retention profile, should be selected in the coro by default and 4 other values added to it. I’ve got it working with getCustomCombo but I get an error “c is null”. Here is what I have so far

            function doInitGrid()
            {
                mygrid = new dhtmlXGridObject('mygrid_container');
                mygrid.setImagePath("<?php echo base_url()?>images/imgs/");
                
                mygrid.setHeader("Server Ip, Server Name,Backup Server,Path,Retention Day(s),Tape Frequency,Backup Frequency,Type,Retention Profile");
                mygrid.attachHeader("#text_filter,#text_filter,#text_filter,#text_filter,#text_filter,#text_filter,#text_filter,#text_filter,#text_filter");
                mygrid.attachEvent("onEditCell",editCell);
                
                mygrid.setInitWidths("90,*,90,*,70,110,*,90,150");
                mygrid.setColAlign("left,left,left,left,left,left,left,left,left");
                mygrid.setSkin("light");
                mygrid.setColSorting("str,str,str,str,int,str,str,str,str");
                mygrid.setColTypes("ro,ed,ro,ed,ro,ro,ro,ed,coro");

                
                mygrid.init();
                mygrid.parse(array,"jsarray");
                array[array.length] = '';
                for(i=0;i<array.length;i++)
                {   
                    retentionProfileCombo(i+1,array[i][8]);
                }
            }

            function retentionProfileCombo(rId,$setValue)
            {
                var combo = mygrid.getCustomCombo(rId,8)
                for(j=0;j<allRetentionProfiles.length;j++)
                {
                    combo.put(allRetentionProfiles[j][0],allRetentionProfiles[j][0]);
                }
            }