Thread:Project:Support desk/Show WikiTextEditor and Show RichTextEditor option not avaliable/reply (15)

That may be the case in case others can not start wysiwyg at all.

If problem is only with toggle link which is used to switch between wikieditor and wysiwyg editor, then problem may be one of these:
 * setting in user preferences (=use of toggle link disabled)
 * version of wysiwyg used may not support wikieditor or wikieditor extension is not installed or activated in LocalSettings.php
 * version of wikieditor is not batched to be compatible with wysiwyg
 * some weird browser issue

Version "1.5.6_0 [B551+12.01.2015]" should work because it contains both wysiwyg and wikieditor which is modified to be compatible with wysiywg. How other versions behave, I can not tell anything for sure.