Positive blue dye but negative pink dye???

[BreeAnnaV]

I took a blue dye test last night (not FMU) and I got a faint positive - the thick line showed up within one minute - its not an evap because the line is as thick as the control line & is blue in color. I ran to Walmart and grabbed some pink dye first response tests - took one last night, negative and took one this morning with FMU and also negative.

 

[CheshireDucky]

How many DPO are you? It's possible that the first response isn't as sensitive as the blue dye. I know people have been having problems with first response since the sensitivity can be off on them.