problems with field-Index while accessing

[NULL ! NULL !]

What you should know:
There are two 5.1 Community-Servers. The one at my developer machine and the one at the customers server.
I exported the database on the customers server and imported it on my machine. The databases are exactly the same. Field 43 (if you start to count with 0) is a field from type integer, field 44 is a date.

My problem:
On my developer machine I get no exception if I access the field 43 (if you start to count with 0). The same EXE brings up an exception on the customers server. Remember! Same DBS - Version, exact copy of the DB! On the customers server. I can't access the field 43 as a number. I get the error that the field named "angelegt" is a date. But the field "angelegt" is the field 44 if you start to count with 0. Again, the same EXE which access the same field works well on my developer machine and use the right data. I do the access with [some source].fields[43].AsInteger.
Field 43 seams to be the correct field on my machine but not on the customers server. Same DB! Same DBS - Version!
I guess one server starts to count with 0 and the other with 1.

Now the question:
Is there a special possibility, that both server starts to count the fields of a table in different way? One with 0 and one with 1? A system variable or such thing?

Maybe I am to blind to see my mistake at the moment... :/

Looking forward to your answers and please excuse my horrible English!