Multirow header sorting arrow displaying problem

When I click on second row of header, the sorting arrow display in the same column, but on the first row, not second. How to resolve this problem?
I use this methods to create my headers

myGrid.setHeader(“A, #cspan”);

Unfortunately the problem cannot be reconstructed locally.
Please, refer to the following snippet:
If the problem still occurs for you please, provide a similar snippet or a complete demo, where the problem can be reproduced.