Verb Tense Shift

When there is a change from one verb tense to another within a sentence or paragraph, it is referred to as a verb tense shift. Every sentence and paragraph should remain consistent in verb tense.
Example of a verb tense shift: Because there are no rooms left at the hotel, we had to camp on the beach.
Corrected sentence: Because there were no rooms left at the hotel, we had to camp on the beach.