Conditional formatting around blank cells

I often have a column that has some cells with numbers and others with blanks. My goal is to get certain numbers to stand out and when I conditionally format the blank cells often get colored, which I do not want.

I searched the internet and found a solution that makes sense but is not working. The attached screenshot illustrates the problem. You can see blank cells colored red.

The complete first formula is: =ISBLANK(AI4172)=TRUE

The range of cells I'm trying to format is AI4172:AI8307.

What's wrong?

Mark