Signing problem

I previously had posted a problem I had getting a manifest to embed and not corrupt the .exe. I believe I have that solved. Now, however, a new problem: I cannot sign the new .exe file! This command line:

signtool sign /a app.exe

causes the error "SignTool Error: ISignedCode::Sign returned error: 0x80070057
The parameter is incorrect."

This command works fine on an exe that does not have a manifest.

Any ideas?

[464 byte] By [JeffreyMcKay] at [2008-1-2]