 -- Three days before voting begins, residents around Iowa are making plans to caucus, but new online tools launched by both the state Democratic and Republican parties designed to inform people where to go Monday evening were built with one major hole, the parties confirmed to ABC News.

The systems were only built off the list of registered voters' addresses. As a result, for new voters who have never registered in the state and who live at addresses where no one else has registered, the online feature does not work.

Instead, when an address is not found in the system, users are confronted with a complicated set of instructions, telling them to look up their precinct name on the Iowa Secretary of State’s website, and then return to the parties’ websites to look for the caucus location for that precinct.

The process requires multiple steps and users must flip back and forth between three webpages. Both party websites also tell people they can call the party offices if they are confused.

In Iowa, voters can register on site the day of the caucuses. The only catch: They need to go to the correct precinct site.

"The caucus locator tool uses the best possible data to match registered voters with their caucus locations, and we are confident it serves the vast majority of caucus-goers well," Sam Lau, communications director for the Iowa Democratic Party, told ABC News. "For those Iowans whose addresses may not be registered by the tool, there are a host of other ways both on and off our website to find their caucus location, and of course Iowans are always welcome to reach out to the Iowa Democratic Party with questions."

Charlie Szold, the Republican Communication Director in the state, echoed the Democrats and defended the system.

"Unfortunately, there is no perfect, easy way to do it," Szold said in an interview, explaining that new voters can find their precinct's name on the Secretary of State's website and then return to their party's page for the caucus location details. Szold said the party was trying to communicate this crucial information in many ways.

"We publish the locations in local newspapers," he said. "Campaigns do a great deal of advertising and educates voters on caucus locations. This is more than we have done in past caucuses."

On the Democratic side, both the Bernie Sanders and Hillary Clinton campaigns have embedded the state Democratic Party's tool on their websites as well.

Members of the Sanders campaign said they were reaching out to voters in many different ways to make sure they knew where to go Monday evening, but they added that the gaps in the tool were worrisome.

"This problem impacts young people and new caucus-goers the most," Kenneth Pennington, the Sanders campaign's digital director told ABC News. "As a campaign, we're going to do everything we can to make sure our supporters know exactly where to go on caucus night."

On the campaign trail, Sanders often notes that increasing and expanding voter participation is key for the future success of the party as a whole and his campaign in particular.

"What we need to do is to reach out very significantly to non-traditional voters, to the younger people, to working people, to many people who have given up on the political process," the Vermont senator said this week.

Clinton's Iowa spokeswoman, Lily Adams, told ABC News the campaign was using "a variety of tools to ensure Iowans know where their caucus is located."

"In addition to the online look-up tool, Iowans can call our hotline, we send information by text message, campaign literature and email, and talk directly with Iowans during phone banks and door to door canvassing," Adams said in a statement.