Hello. I am teaching myself lipsync in Blender. While creating lipsync phenomes with my character, an error occurred. The influence slider for the shape keys has disappeared. To this effect, I cannot turn shape keys on or off.

Above is an image of the character for which I was building phenomes. In the “shapes” box, there is no slider for turning the shape on or off.

Alternatively I concocted an experiment where I took the default Blender cube scene and started creating random shape keys for aforesaid cube. Strangely enough the shape slider toggle is now present.
Not sure what to do. Someone help? Thanks in advance.
-Anayo