I know this is going to seem like an easy question, but I can't find the right syntax to handle it!

I have a string...

mystring = 10,11,12

and I am looping through a set of numbers i = 1-20

In the loop I compare i to mystring, and if the number in mystring is equal to i then I mark the check box as selected.

My problem is when I say Instr(mystring,i) and i=1 (for example) it is true because there is a 1 in the string, but it's not the truth I want because it's not 10,11,or 12.

I think I did a bad job of explaining that but if anyone has every handled this situation it would really help me out!