Fix my and program and improve it.

Hi my name is Brendan and I work in a very small not for profit medical research lab in Ballarat Australia. We have a visual basic program which we use to manage patient sample vials stored in liquid nitrogen. The program is coming up with an "run time error 91 " message. None of us here know visual basic or how to fix the problem. Also we are concerned we may be hitting the storage limits for the program. What I would like to do is to post a copy of the program with sensitive data redacted for some one to to fix the problem (runtime 91) and check to see if we still have room to continue to add data and modify the program if needed to improve it. The program is designed to inventory vials stored in liquid nitrogen tanks. Each tank has 6 Racks , each rack has 8 boxes , each box contains 100 vial positions. so vials are stored for example as T2R3B4P36 ( Tank 2 rack3 box 4 position 36) . each vial has data associated with it e.g date stored , disease type. The program was developed from a legacy excel spreed sheets so some of headings may appear odd . for example a column headed "comment" should be called "Codes". which may be a good example of something which could / should be changed. Also because we have multiple users the way some of the data is entered is not consistent. we currently have six tanks but that will increase by at least one tank per year so we need to be able to continue to add data with out hitting any design limits. the vials are also di- identifed to so patients names are not used. A code is assigned to a patient and any additional samples received from a patient are assigned the same code. The program consists of six linked excel sheets : A home page for entering and deleting patient data, a master list which has the patients name and assigned code, a page listing all the vials for each patient, a list of all the vials in all the tanks and a list box for adding tanks and codes for patient samples ( the list box was originally set up for three tanks but we now have 6+ so it would be good if we could modify it) and finally a sheet listing all the vials used and deleted from the system. it would be great if somebody could take this on and: 1) Fix any bugs. 2) Check the design limits (if any) for adding data 3) suggest and implement any design changes and improvements in consultation with me. I look forward to your replies and getting this problem fixed .