cannot evaluate at compile time

[anter003]

    proc parseStringSeq*(text: string, charset: CHARSET): CHARSEQ =
        var osq: CHARSEQ = @[]
        for i in countup(0, text.len - 1):
            if text[i].isAlphaAscii():
                osq.add(charset[int(text[i]) - 63]) #alphabets(capital)
            elif text[i].isDigit():
                osq.add(charset[int(text[i]) - 2]) #digits
            else:
                discard
        return osq
    
    
    Run

This is a shoddy proc for taking a string and converting into other type char 
by char. And when I try to run it it says `cannot evaluate at compile time: 
text`. If i replace string with static[string], it says `cannot evaluate at 
compile time: i`.

I have a hard time understanding why this error happens.