Since you are fairly new to the forums, you may want to review this article: 10 Commandments for the OTN Forums Member. Following the guidelines in this article will ensure you have a positive experience in any forum, not just this one.
Having said this, you should always post the following information when asking a question in this forum:
1. Forms version (eg: 126.96.36.199.0 not 11g).
2. If Forms 6i, is your app web deployed or Client Server?
3. If Forms 9i or higher, what is your Java version, Internet browser version, and the client OS version.
4. Always, always list the full error message you are receiving.