In my database I have a foreign key field that is an integer and accepts nulls because in some situations the user can't provide a measurement. When I create a new record from DotNetNuke it throws an error about foreign key conflict because it saves it as 0 by default while there are no 0s in the lookup table. In my info class, I have changed the field type from int to int?

That solved my problem. However I come across another situation where I can retrieve records that have the foreign key set to null, but any records with a measurement value throws an error below when the stored procedure is executed:

A critical error has occurred. Invalid cast from 'System.Int32' to 'System.Nullable`1[[System.Int32, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089]]'.

Here is my property from the info class that stores the foreign key field:

private int? _EQSWLMeasurement

public int? EQSWLMeasurement
{
get
{
if (_EQSWLMeasurement.HasValue)
{
return (int)_EQSWLMeasurement.Value;
}
else
{
return null;
}
}
set
{
_EQSWLMeasurement = value;
}
}

Any idea how I can fix the issue, or is there anything obvious that I've missed out?