Midi thru problem

[Pete]

When I start my Cubase VST, or any other midi editing program, my midi thru stops working.

I've got a Roland A30 midi controller. This goes with midi out into my midi interface mpu401 into my computer. From the mpu401, the midi out goes into my Roland Sound Canvas midi in.

This setup worked 100% fine with my previous computer in both Windows 3.1 and DOS where I used programs such as Cakewalk professional.

Since I've upgraded to a new pIII 500mhz running Win98, I've got a midi thru problem. Midi files play perfectly through the setup. However, when I try to record anything, nothing happens. No sound to my Canvas. IF i hit Cakewalk's panic button, a couple of notes slip through simultaneusly.

Could this be a driver problem? My win98 setup recognises that I've got a MPU401 and it plays midi perfectly. When WIndows startup, I can also hear what I'm playing through the Canvas. It is just when I start a music program such as Cakewalk Pro or Cubase VST, which I'm using for my audio and which I want to use for midi, that the mid throu seems to fail.

Can anybody help.