$1 and $2 do not have values inside icfb. You have to create a new SKILL function with the values from $1 and $2 in the function call. That is why I included the echo statement above, the $1 and $2 values are put into the function runMySkillFunc.il and when it is loaded the function is executed with the values.
In addition, the replay file does not automatically load the file ab.il. That is why I had the load statement in my echo output above.
For your problem you need to create a file, we will call it runab.il. It should contain the following statements which could all be on the same line:
ab( "analib" "diglib" )