[2005] Select not returning correct rows

[penguin5000]

I am writing some code that interrogates a database of error codes, and areas where the error code may occur so that I may provide the user with common problems and solutions to the error.
For example, I have an error code, "abc" which could occur in Module1, Module3 and Module7.
What I am finding is that if I also have an error code "ABC" (i.e. uppercase), when I run the following select command, it returns DataRows for "abc" and "ABC".
If I select "abc" from my DropDownList, how do I get it to only select "abc", and not "abc" and "ABC"?

strExpression = "Code = '" & Me.DropDownList2.Text & "' and Module = '" & strModuleCode & "'"

Dim foundrows() As DataRow
foundrows = dsDataSet.Tables(2).Select(strExpression)