Difficulty with conditional formatting formula

I have a table, and I'd like to color code the cells in it in a specific manner. When the value in the cell reaches a target value, I want the cell to be green, when it reaches a specified interim value, I'd llike it to be yellow. 

Getting the green formatting to work was relatively painless.

The target value is kept in a separate sheet and I can look it up quite easily. This part works, here is the formula I have in my conditional rule: 

=A1=Maxima!A1

Now my difficulty/issue is in applying a conditional format to highlight the interim values. . The interim value is approximately 0.806494192 of the target value - give or take one or two to allow for rounding errors 

To clarify: assume cell C11 has a target value of  24,007,200 then, if it has a current value of 19,361,668. it meets my criteria. Similarly, if cell G11 has a target value of 14.050,080, and it reaches 11,331,308, it meets my criteria. 

Because the numbers are so large, there can be a +1/-1 error in simply multiplying the factor (0.806494192) with the target value to determine if the cell has reached the required  interim value.

To resolve this, I'm needing a condition that tests true if the value in the cell is within +1/-1 of the required value. and then color it as such. 

If I type this formula in a cell, I get the "true", which is what I need: 

=IF(ABS(Maxima!C11*0.806494192-C11)<5, "true","False")

But for the life of me, I can't figure out how to put that into the conditional formatting  formula box. 

If anyone here can follow my explanation here, I'd really appreciate a helping hand/suggestion. 

Thanks!