signature validity

[Rotto Rotto]

Hello, 

We use Wacom Sign Pro PDF app to sign documents. We sign it - signature is valid - and saved it in PDF file. When we open it in Nitro Reader it says the signature is invalid.

Usually the first signature is with red cross and the last one has always green checkmark. Signatures between them has green checkmarks AND yellow triangle with black !.

How can I fix it? This is very urgent. We send contracts to authorities so we need it to be correct.