A little confused !? Please help

Trisha
Hello ladies 
Ok according to glow I am in my FW but I am currently using opk called ANSWER and keep getting a negative LH surge.... I have never used opk before this is my first time I am on CD17 (this pic was from yesterday) these are my test for the last 4 days does not look like its getting darker to me ..... Should I try different test or is it that I have not ovulated yet ?