Ti 89 Graphing Help: Fixing "Not an Algebraic Expression" Error

[whitneysit]

So I have a project due tomorrow and I really need to use a caculator and Mine won't work right.

When insert
-1x/(x<o)/(x>-1)

It saids its not an algebraic expression how do I fix that.
I try it with an ti 84 and it worked.

 

[ranger]

Have you tried clearing your variables? Maybe try something other that x, such as y, z, t, or even xy (which is not the same as x*y).