Limited number of columns in a matrix in PowerPoint

Hi all,

I am trying to insert a 16*16 matrix in PowerPoint. I right-click an element in the matrix, and then click 'Insert Column After' in 'Math Options'. It only allows me to insert up to 15 columns in a matrix. No limit in the number of rows that can be inserted is seen though. Any suggestions? I'm using Office 2013 on Win7.

Thanks,