Purdue ChE delaying official offer?

[Zhongyu Zou]

I received the email from both PhD in Chemical Engineering and Chemsitry in late January and I decided to accept the ChE. Then the administrative staff told me I had to first reject the offer from Chemistry and then they'll be able to update the application status in the online application system. I did so and up to now they still did no change, recently I emailed them and they told me the offer I received was just the recommendation that I get admitted, and they are still working on the final decision on the graduate school level??

Is there anyone who have experienced this sort of thing? Is there any chance that they'll reject me? Then I'll be giving up the offer from chemistry in Purdue for nothing? I'm kinda desparate, any help please....