jQuery Grid Plugin - jqGrid

I am new to jqGrid (many thanks Tony!) and I am moving from a standard grid to the editable grid and have run into this error:

jQuery(modwin).jqDrag is not a function

DnRModal("#editmoduserGrid", "#edithduserGrid td.modaltext")grid.common.js (line 66)

(?)()grid.formedit.js (line 215)
nodeName(Object 0=table#userGrid.scroll length=1 jquery=1.2.6,

updateNav(cr, totr, rid), undefined)jquery-1.2.6.min.... (line 21)

size(updateNav(cr, totr, rid), undefined)jquery-1.2.6.min.... (line 12)

editGridRow("1", Object top=10 left=10 width=300 height=280 modal=false)grid.formedit.js (line 164)

(?)()user_all.html (line 38)

trigger(Object originalEvent=Event click which=1 view=window)jquery-1.2.6.min.... (line 26)

unique()jquery-1.2.6.min.... (line 25)

jQuery(modwin).jqDrag(handler).jqResize(".jqResize");