RadGrid - Client api - get_insertItem() throws TypeError: a is undefined

[Sven]

I'm using the client side api to set a radgrid to insert.  I'm then trying to get access to the HTML of the insert item by calling 
get_insertItem(), but I'm getting this error:

TypeError: a is undefined
http://localhost/Telerik.Web.UI.WebResource.axd?_TSM_HiddenField_=RadScriptManager1_TSM&compress=1&_TSM_CombinedScripts_=%3b%3bSystem.Web.Extensions%2c+Version%3d4.0.0.0%2c+Culture%3dneutral%2c+PublicKeyToken%3d31bf3856ad364e35%3aen%3ac9cbdec3-c810-4e87-846c-fb25a7c08002%3aea597d4b%3ab25378d2%3bTelerik.Web.UI%2c+Version%3d2012.1.501.40%2c+Culture%3dneutral%2c+PublicKeyToken%3d121fae78165ba3d4%3aen%3a5032a904-f84e-4114-98a5-b1bfc16b2dec%3a16e4e7cd%3aed16cbdc%3a874f8ea2%3af7645509%3a24ee1bba%3ac172ae1e%3a19620875%3af46195d3%3a9cdfc6e7%3a2003d0b8%3ae330518b%3a1e771326%3ac8618e41%3ae4f8f289%3a86526ba7%3a490a9d4e%3abd8f85e4%3a39040b5c%3a11a04f7e%3a7165f74%3ab7778d6c%3aaa288e2d%3aa51ee93e%3a59462f1%3a58366029%3a68f76a79%3af85f9819%3a52af31a4%3a2a2fc429%3addbfcb67%3a8e6f0d33%3a6a6d718d%3a82923ac3
Line 21801

mtv.showInsertItem();

if (mtv.get_isItemInserted()){
    var insertRow = mtv.get_insertItem();    // <--- this line throws error

[Kostadin]

Hello Sven,

I was not able to reproduce the issue on my side. I prepared a small sample and attached it to this forum post. Could you please give it a try and let me know how it differs from your real setup?

Regards,
Kostadin
Telerik