Script Error on aspx page: running .NET 1.1 on 64

Question

I have a namespace like this in one of my aspx pages (.NET 1.1)

<%@ Register TagPrefix="jwg" Namespace="Janus.Web.GridEX" Assembly="Janus.Web.GridEX" %>

This code used to run alright in .Net 1.1 on a 32 bit system but recently we are porting it to 64 bit system (only the run time not the development environment). It has already been ported successfully on one 64 bit system - however that was done like months ago and I have now completely forgotten what all settings were done at that time (and unfortunately I did not take any notes at the time).

Everything runs fine except for few pages where I use the above mentioned namespace registration tag. It is throwing me a script error error at run time from browser saying that An error has occurred in the script on this page. Error: 'GridEx' is undefined. Do you want to continue running scripts on this page? The DLL in the bin is same as it is in on the another 64 bit working box. All other setttings on IIS seems to be working fine since I was able to set .NET 1.1 app pool on it and run the entire application.

Thanks.