Hi Eric -
I have seen this error before - usually the dll has been created with VC++ 6.0 and CVI 5.0 does not understand the new 6.0 import library format. You have several options:
1. get CVI 5.5.1 - it understands both VC++ 5.0 & 6.0 import formats
2. if you have the source code for the dll,
add the 5.0 link option to your VC++ projecy by
A. Go to Project >> Settings >> Link Tab.
B. In the link options box type /LINK50COMPAT
3. Alternatively, use CVI to open a header file that prototypes all of the functions exported from the DLL, and then select CVI's Options >> Generate DLL Import Library to generate a *.lib file that you can successfully link in your project.
This information is alos available on our external help site, www.ni.com/support, search for "Bad h
eader encountered" or Document ID 1DNEQDNU.
good luck
ben schulte
national instruments