Really Frustrating

I have just published a paid post in my blog but I have problem submitting the post to the advertiser. I keep getting a message stating that the link is not properly placed in my post. I have copied and pasted the codes to the link countless times from the advertiser's website to my blog post and have even switched the mode to Edit Html but still kept getting the error message. This is really driving me crazy and I have many posts with deadline expiring today and tomorrow.