MicrostockGroup

You seem to need to log in to photobucket to see your images.

I can see your photos. Here is what I think. First, all images submitted here are the same subject (except one with a flower). The image number 2 has blown-out sky and the part of the building on the right side. Also, this image looks like you applied too much of contrast, and/or sharpening. You should straighten the horizon on the image taken from the top of the tower. The first image looks blurred on the left side...check that out, I'm not completely sure because I can't see it at 100% size. I don't think this flower will pass the application. If you want to take the image of a flower it should be really extraordinary, and not just beautiful. They have tons of flowers.
Do you need a property release for any of these buildings? Did you erase every logo?
Otherwise, we can't see images at 100%, so we can't judge about noise, artifacts or banding because of overprocessing.

You are not bad at all. These are all small things, but for the application, you have to pay attention on them too.

I got accepted at Istock not long ago. I also got rejected the first time for one reason - there is no diversity in your photos. That is exactly what happens with you, too. You need something more than just travel photos(lifestyle, still life, sports, food, anything goes). You have to show your photography skills and potentials.

I have a friend in the same boat - accepted to other sites no problem but had so many rejections with iStock that she almost gave up. She finally has been accepted, so keep trying

(For me it's Shutterstock - 8 out of 10 of my initial submission was rejected - ouch!!  Meanwhile I've been accepted to iStock, Dreamstime, Fotolia, BigStock, Deposit Photos, and CanStock, so I'm definitely not giving up on Shuttestock

Anyway, I posted these on another thread, but I'll post them again in case it helps... these are the three pics that got me accepted into iStock. Good luck, and don't give up!

Thanks, everyone for the advice and encouragement...I know my pics are not very "microstocky" - I'll try to add some quality still lifes of various objects to the mix.  I've also taken to carrying a monopod with me to help with focus issues.

+1 - plus, SS hates shadows. The bridge next to the House of Commons in London was the main focus, yet most is in the shadow. That's a NONO for SS. The OP should learn to shoot with the sun at his back.