I'm having the following problem when using reflection.

The following statement evaluates to false:

```
object[] attributes = someType.GetCustomAttributes(true);

if (attributes[0] is NUnit.Framework.TestFixtureAttribute)
    return true;

```

However this evaluates to true:

```
object[] attributes = someType.GetCustomAttributes(true);

if (attributes[0].ToString() == "NUnit.Framework.TestFixtureAttribute")
    return true;

```

Any ideas why?