The first argument of the FillColumns method is a FPScript formula which will be evaluated to produce a data series or data matrix to be assigned to the component specified as the second argument. The variable i is predefined and holds a data series of index values 0, 1, 2, 3 and so on.
In your code you are using a second variable Step which is decraded on the VBA level but not for the FPScript function. To solve your problem you may either exchange Step by the literal constant 0.1 or add the following code to the FPScript formula:
Step = 0.1
(NumberOfValues(i), FloatingPoint32 1,FloatingPoint32 Step )
Hint: If you switch on macro recording and the use the command “Fill column with values” you will see that FlexPro uses an FPScript with delarations as given above.