EXCEL 2003 right function not recognising <100

hi
I am running a spreedsheet based around various reports.
each repot has it's own name & number which increases in increments of 1.
I use the mid function to as a calculator to alter report numbers.
this works fine after 100 but for numbers not of three digits it returns only 2
ie stop.001 returns stop.02(not stop.002)
the formula i use is
1. first cell A30 = stop."&"015" (this is a manual field)
2. second cell = "stop."&(RIGHT(A30,3)+1
can someone please explain what the problem is
thank in advance
Rayo