Additions Needed to Existing PHP Form

I have had a previous coder (from RentACoder) set up an existing "Make An Appointment" form in PHP using a javascript that allows a web visitor to select a clinic location for the appointment and then choose from a list of doctors from that location. Here is a link to the existing form. LINK- [login to view URL] Everything seems to work correctly at this point except for the fact that if the web visitor does NOT select a clinic location NOR a doctor from either pulldown list and then submits the form, it returns an "Internal Server Error". I would like for someone to edit the existing page (or create a whole new form if you prefer) and add the option to require or check and see if the clinic pull down has been selected. If it has not been selected, it should return an alert, "Please select a clinic location". I also have noticed that when I am filling out the form, when I press the "tab" key to jump to the next form field, it is skipping ahead from the "Last Name" field to the "Email Address" field. If we could fix this "onFocus" issue as well, that would be great. If you have any additional questions or comments feel free to contact me and I will try to help. Thanks to all the participants! ## Deliverables 1) Complete and fully-functional working program(s) in executable form as well as complete source code of all work done. 2) Deliverables must be in ready-to-run condition, as follows (depending on the nature of the deliverables): a) For web sites or other server-side deliverables intended to only ever exist in one place in the Buyer's environment--Deliverables must be installed by the Seller in ready-to-run condition in the Buyer's environment. b) For all others including desktop software or software the buyer intends to distribute: A software installation package that will install the software in ready-to-run condition on the platform(s) specified in this bid request. 3) All deliverables will be considered "work made for hire" under U.S. Copyright law. Buyer will receive exclusive and complete copyrights to all work purchased. (No GPL, GNU, 3rd party components, etc. unless all copyright ramifications are explained AND AGREED TO by the buyer on the site per the coder's Seller Legal Agreement). ## Platform Mac and Windows compatible, all 3.0+ versions of all browsers