I believe the flexcel.dll is a 32 bit dll. Is this correct? Is there a 64 bit version?
Flexcel.dll is both 32bit and 64 bit at the same time. It is compiled as "any cpu", and this means that when you call it form a 32 bit app it will be a 32bit dll, and when called from 64bit it will be a 64 bit dll. What it is depends on what your main app is.
This is possible because it is fully managed and it doesn't p/invoke any 32 or 64 bit dll, so the IL will be converted to 32 bit or 64bit assembly code depending on what is needed.
We test both versions here by calling the dll form a 64 bit app and a 32 bit app, and both work well. One interesting thing is that 32 bit is consistently faster than 64 (this happens in .net and also in delphi). In older .NET frameworks like .NET 2.0 difference was very big (like 2 times slower for 64 bit), but in .net 4 finally difference is very little (even if 32 bit is still a little faster)
Adrian Gallero2012-04-19 09:19:29