Custom Assembly Behaves Differently In The Report Designer And Report Manager

Hello everyone,

I created a custom assembly using C# to transform some binary data into text, and in this assembly I used one win32 dll developed by our customer to help me to do the tranformation.
The code I used to call the win32 dll is like below:
[DllImport("tdasuie.dll", EntryPoint = "AlrtLogConditionToText",
ExactSpelling = false, CharSet = CharSet.Auto, SetLastError = true)]
private static extern UInt32 AlrtLogConditionToText(Byte[] pbCondition, StringBuilder pszText, UInt32 dwSize);

I defined a C# method to call the above win32 method and return a string. Then in the report, I called this C# method to get the correct string.

In the report designer, the C# method in the custom assembly can return the correct string in the preview window. But after I deployed the report into the report server, the textbox will only display "#error" in the report manager web page.

Can anybody help me on it? Thanks a lot.

Danny