SqlCe Ntext Data Types And VS2005

I have an application where I'm trying to store xml data in a db field defined as ntext. I have a dataset and table adapter setup in VSNet 2005 and SqlCe 3.1. When I look at the table adapter in the VS designer it shows the field with a type of String and a size of 2147483647 which appears to be correct. Also, if I look at the code generated by the MSDataSetGenerator tool it shows the parameter defined in the same way as in the following
param = new System.Data.SqlServerCe.SqlCeParameter();
param.ParameterName = "@Questions";
param.Size = 2147483647;
param.IsNullable = true;
param.SourceColumn = "Questions";
this._commandCollection[2].Parameters.Add(param);

My problem is that when I run the application and try to insert an item into this column the application throws an exception related to corrupted memory. Trying to debug the problem I found at run time, the param.Size value for the ntext parameter had been set to 255. Since the specific xml I was trying to insert was 410 characters in length I'm guessing that this is what is causing the crash.

Is the expected behavior (the setting of the size to 255 that is)?
If not, am I missing some trick here?

Thanks
Neil