I am attempting to automate a process that creates a series of workbooks each
with a different subset of data populated. The basic process is running fine
however I have a number of user defined functions (UDF's) implemented via an
automation add-in. If I load my newly created workbooks programatically using

Excel._Application excelApp = new
Microsoft.Office.Interop.Excel.Application();
Excel.Workbook doc = excelApp.Workbooks.Open(myFile, missing, missing,
missing, missing, missing, missing, missing, missing, missing, missing,
missing, missing,missing, missing);

My udf's are not recognized and return #NAME?

When I open the workbooks in a normal Excel session launched from the start
menu they behave correctly.

It would appear that I need to do something to force the automation dll to
load in this scenario?

Any help would be appreciated.

Regards

Andrew Wiles