Using Tables and New Form Entry with linked sheets

[Jowatana]

I have a workbook with 3 sheets. Each keeps track of entries however certain cells contain formulas (Vlookup, IF, etc.) that reference both cells on the current sheet and cells in another sheet. Since I wanted to make sure I could sort and find entries based on data types within each sheet, each sheet is set up as a table. What I am finding is that creating a macro to unprotect the sheet and then open the form entry "new" results in an error, cannot extend table or database. Since many users will be opening the workbook and have even less technical knowledge than I do, I want to make entering records quick and simple utilizing a form or something similar while protecting the formulas. From my understanding, keeping the data in a table appears to be causing the problem but is there a way around that? Somewhat unrelated, is there a way to adjust the Vlookup range dynamically? Perhaps, I am making this more complicated that it needs to be but Excel is not a familiar program - neither are forums so thank you and I apologize if I have overlooked some protocol here.