Could you tell me what it means that PC1 is 100% from PCA analysis?

I am completely new to PCA analysis.
I followed a script but my result showed 100% PC1 and 0% PC2. I am afraid that my data input was not right or something...
Thank you for the response. No, it is a dataset from RNA-seq on two sample groups (3 samples per group), so it contains about 20000 genes as variables.
The values are the relative frequency of the events. They are all between 0 to 1.
Do you think it influence the result?