Array Looping Problem

I am looping while both arrays are les than or equal to their ubound limits.
I want to do a strComp and increment the i or j counters as below, depending on the outcome of the string.
 
The problem is, when I run the program and feed it two arrays, the page either hangs and does nothing or I get an out of bounds error on i or j.
I need this function to work when the arrays that are being passed to it are of different lengths.
 
ANY help woul dbe wonderful, thanks in advance :)
 
----code---
function localTextMetric(tsortedTargetArray, sortedQueryArray)
 
do while i <= ubound(sortedTargetArray) or j <= ubound(sortedQueryArray)
 
                        if i<= ubound(sortedTargetArray) or j<= ubound(sortedQueryArray)then
                       
                        alpha = StrComp(sortedTargetArray(i), sortedQueryArray(j))
           
                                    if alpha = -1 then
                                    i = i + 1                       
                                    elseif alpha = 1 then
                                                j = j + 1
                                    elseif alpha = 0 then
                                                i = i + 1
                                                j = j + 1
                                                intersection = intersection + 1
                            end if          
                        end if  
            loop
 
response.write(i)
response.write(j)
response.write(intersection)
 
end function

get the lower value first then set the loop to use that number.  don't try to do concurrently