Question : SSRS Bigint Data Type Export Problem

Version  SQL Server 2005

Hi,
I have a report that has a binary field which is the Unqiue Id column needed for a report.
In SSRS I used a convert and converted this unique Id column to Bigint.
On using the export option to excel or .csv this column is amended and the values are not coming out correctly and giving duplicates. However in the report displays correctly.
Just seems the export and probably excel restirctions changes the values.

Any suggestions on how I get use this column in SSRS and successfully export to Excel.

Basically I just need the column to be a unique Id that can be used to identify each row through SSRS.
My column can't be converted to Int as it's too large.....
I just need something I can use through SSRS that will deploy and export successfully as a Unique Id into Excel.

Any suggestions ?

Answer : SSRS Bigint Data Type Export Problem

But how about converting binary to bigint and bigint to varchar?