These TaqMan Advanced miRNA array cards enable profiling of over 300 distinct miRNA targets on a single card. Given the numerous targets and your sample's nature, some miRNAs might not be expressed or may be at low levels, leading to less-than-ideal amplification plots for all spots. Sample quality or input could also be a factor. Ensure you verify the RNA sample's concentration and quality before reverse transcription, and check the Ct values for endogenous control assays on the card to confirm they're within expected ranges for typical samples.