Thank you for contacting us, and I'm sorry for the issue you are experiencing. When you enter your password, mSecure simply uses the characters you enter to decrypt a know piece of text that was previously encrypted by the password you entered when you created the account or last changed your password. If the data can be decrypted, then mSecure knows it's the correct password. If the known text can't be decrypted, then it knows it's not the correct password and shows the message that the username and/or password is incorrect.
Real quick, when you open mSecure, do you see a little blue face icon in the bottom of the screen?