setting colspan using insertcolumn

I’m trying to use the #colspan header item in my columns i am inserting using .insertcolumn() , but it doesn’t render, it just shows the text #colspan .

I also tried the setcolspan function as well, but it errored out with (Error:d is null)

I have also made sure enableColSpan(true); has been set before.

Any ideas?

Unfortunately it not possible to merge column in header of the grid when you inserting column