Write table blob field to file

I have a table with blob field and some others as well. I am trying to read blob field and save it to file using IBlobStream, and the thing compiles. The problem comes up in run-time, when calling blobStream.SaveToFile() method, saying:

'object' does not contain a definition for 'SaveToFile'

the following code:

int blobFieldID= table.Fields.FindField("MODEL_NAME");
int nameFieldID= table.Fields.FindField("MODEL");
ICursor cursor = table.Search(null, true);
IRow row = cursor.NextRow();
while (row != null)
{
    IBlobStream blobStream = (IBlobStream)row.get_Value(blobFieldID);
    blobStream.SaveToFile(@"C:\TEMP\" + row.get_Value(nameFieldID) + ".tbx"); //error
    row = cursor.NextRow();
}

When i hover mouse over SaveToFile method it says:

(dynamic expression)
This operation will be resolved at runtime

I can't figure out what's the problem in here