DNA fragments observed in agarose gel are not visible in capillary electrophoresis

Hello, as a laboratory, we are a 12-row 5200 Fragment Analyser user. We are having problems getting results for our SSR-based experimental studies. When we load our samples to the device after PCR (5ul PCR sample + 19ul Dilution Buffer), we expect to see a band profile of approximately 200-300bp. However, the results we get are as if the reaction never worked. Then, when we load the same sample in the same volume (5ul) on agarose gel at 1.5% concentration, we can see DNA fragments of the size we expect. So the PCR is working.

To understand the problem, we ran another set of samples that were tested before the samples mentioned. The results were very good, even though the samples were run a second time and had been in the fridge for more than 2 months. After this run, we again loaded the problematic samples in a different volume (10ul sample + 14 Dilution Buffer) and the result was again negative. Different people performed the PCR and capillary loading steps, but the result was still unchanged.

We are waiting for your suggestions and support.

Here two photos of agarose jel and capillary results.

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