Migrating from VBA to .NET vbModeless

Quick question that can hopefully be answered...

I just migrated an old tool from VBA to .NET and I got all the kinks out except one bit of code that I can't find the answer to...

In VBA, the user form was called with this: UserForm1.Show vbModeless

I have tried to simply enter in UserForm1.Show, or UserForm1.ShowDialog...but neither is working...they both provide me with this error:

"Reference to non-shared member requires an object reference"

I'm assuming there is a reference I need to add?

Thanks so much,